The 20th International Congress of Orientalists was held in Brussels in September 1938. The material connected to this congress is:

• Letter from Dr G. Ryckmans, Institut Orientaliste de l'Université de Louvain, to the Director of the Journal of the Royal Asiatic Society to inform that the place of the forthcoming conference is likely to be in Brussels. Handwritten with printed letterhead, dated 17 December 1937.
• Letter from Col. Hoysted, Secretary, Royal Asiatic Society, to Dr. G. Ryckmans, Institut Orientaliste de l'Université de Louvain, to thank for his letter and warning about the 20th Congress and to state that he had cancelled the prepared statement for the Journal of the Society. Typed, dated 8 January 1938.
• "Première Circulaire" for the 20th Congress to state that it will be held in Brussels from 5-10 September 1938. Printed in French with handwritten annotations, dated January 1938.
• Letter from Jean Capart, Secretary-General, and L. de la Vallée Poussin, President, Organising Committee, to invite a delegate from the receiving organisation. Printed in French with handwritten annotations, dated 10 February 1938.
• "Deuxième Circulaire" for the 20th Congress giving administrative information and providing a form to subsribe to the "Bulletin D'Inscription". Printed in French, dated April 1938.
• "Troisième Circulaire" for the 20th Congress giving more detailed logistical information. Within the circular is a "Bulletin D'Inscription" form partially completed for Louise Wallace Hackney. Printed in French with handwritten annotations, dated June 1938.
• Letter from Louise Wallace Hackney to Colonel Hoysted to state that she had completed and sent a form previously. She is unsure where she will be staying for the Congress. Handwritten, dated 17 July 1938.
• Letter from Thomas Cook and Son Ltd., to Colonel Hoysted to send copies of an itinerary for arrangements for the 20th Congress. Typed, dated 20 July 1938. The itinerary is with the letter.
• Letter from Col. Hoysted to Thomas Cook and Sons Ltd. to thank for the details of their tour to Brussels for the International Congress. Typed, dated 21 July 1938.
• Letter from Thomas Cook and Son Ltd., to Colonel Hoysted to ask whether a venue and date for the next Congress had been decided at the Brussels conference. Typed, dated 21 September 1938.
• Letter from Col. Hoysted to the Secretary General, XXth International Congress of Orientalists, to ask whether any arrangements of the place and date of the 21st Congress had been made. Typed, dated 4 October 1938.
• Letter from Col. Hoysted to Thomas Cook and Sons Ltd. to state he was unable to give any information concerning the 21st Congress. Typed, dated 20 October 1938.

The 21st International Congress of Orientalists was held in Paris in July 1948. Material associated with this Congress is:

• "Première Circulaire" from J. Bacot, President of the Societé Asiatique concerning the 21st Congress to be held in Paris. Printed in French, undated.
• "Deuxème Circulaire" from J. Bacot, President, and R. Grousset, Secretary-General, Organising Committee, concerning details of the 21st Congress. Printed in French, undated.
• "Bulletin d'Adhésion" for the 21st Congress. Printed in French, undated.

The 22nd International Congress of Orientalists was held in Istanbul in September 1951. The material associated with this Congress is:

• Letter from Professor A.J. Arberry, Chairman of the Executive Committee, Association of British Orientalists, to Societies and Institutions to seek their opinion on the proposal to constitute an International Federation of Orientalist Societies which is to be included in the Agenda of the forthcoming 22nd Congress. Opinions gathered will be used to affect any decision taken by the Association of British Orientalists regarding the project. Typed, dated 5 May 1951.

The 23rd International Congress of Orientalists was held in Cambridge in 1954. The material connected with this Congress includes correspondence concerning organising and finance of the Congress, correspondence regarding attendance, General programme, correspondence regarding the publication of the Proceedings of the Conference and a further research enquiry.

The 25th International Congress of Orientalists was held in Moscow in August 1960. The material associated with this Congress is:

• First Circular for the XXVth International Congress of Orientalists from B.G. Gafurov, Chairman, and I.M. Diakonoff, Secretary, Organising Committee, giving details of the dates and sections for the Congress. Printed in Russian and English, undated.
• Second Circular from the Organising Committee to give further organisational information regarding the Congress. Printed in Russian and English, undated. With the circular is an application form for attendance at the Congress, also printed in Russian and English.
• Announcement from the Royal Asiatic Society of the 25th International Congress with the sections and registration fee. Printed, dated September 1959.
• Application form to attend the Congress. Printed in Russian and English, undated.
• Notice of flights to and hotels in Moscow. Typed with handwritten annotations, undated.
• List of British delegates for the Congress. Typed, undated.
• Letter from the International Union of Orientalists to the Royal Asiatic Society to invite the Society to take part in the General Assembly at the forthcoming Congress. Typed, dated 8 July 1960.
• Letter from Denis Sinor to Mrs Davis, Royal Asiatic Society, to ask her to make sure that the Society's subscription is paid to the International Union of Orientalists. Typed, dated 11 July 1960.

The 26th International Congress of Orientalists was held in New Delhi in 1963. These papers concern preparatory organisation. They are:

• Letter from the International Union of Orientalists to the Royal Asiatic Society to enclose the minutes of their meeting in Tokyo, October 1961, and the statutes of the Union. They ask for the Society's to remit their quota to enable the work towards the next Congress. Typed, dated 3 May 1962.
• Letter from the International Union of Orientalists to the Royal Asiatic Society to follow up on their letter of 3 May as they had not yet received a reply from the Society. Typed, dated 3 July 1962.

The 27th International Congress of Orientalists was held in Ann Arbor, Michigan, USA, in August 1967. The material concerned with this Congress includes administrative correspondence and organisation for the drinking horn (see RAS ICO/1) to be at the Congress.

The 28th International Congress of Orientalists was held in Canberra, Australia, in January 1971. The material within these papers includes administrative correspondence, possibilities of affinity flights and transport of the drinking horn.
The administrative correspondence is:

• Letter from A.L. Basham to Secretary, Royal Asiatic Society, to send his subscription and to inform that the Society would soon be receiving its official announcement of the 28th Congress. Handwritten, dated 29 May 1969.
• Letter from Rafe de Crespigny, Secretary-General, International Congress, to send the Announcement and Poster for the 28th Congress. Typed, undated. The printed Announcement is with the letter.
• Letter from Secretary, Royal Asiatic Society, to Rafe de Crespigny, Secretary-General, International Congress, to thank for the Announcement and to suggest he contacts A.L. Basham for further help. Typed, dated 5 November 1969.
• Letter from Jean Filliozat to Royal Asiatic Society to state that he would ensure their letter is delivered. Handwritten in French, dated 17 March 1970.
• Letter from Rafe de Crespigny, Secretary-General, International Congress, to Secretary, Royal Asiatic Society, to ask if the Society could give any help with arranging affinity flights to the Congress. Typed, dated 10 March 1970.
• Letter from Secretary, Royal Asiatic Society, to Sir Harold Bailey to ask his advice on the Secretary-General's letter and the Society's involvement in organising transport. Typed, dated 24 March 1970.
• Letter from Secretary, Royal Asiatic Society, to Rafe de Crespigny, Secretary-General, International Congress, to confirm their support for the Congress and to ask regarding arrangements for hospitality in Australia. Typed, dated 13 April 1970.
• Second Invitation and Enclosures for the 28th International Congress. Printed material, undated.
• Notice from Secretary, Royal Asiatic Society, to fellows to ask whether they would be interested in subscribing to charter or affinity flights for the conference. Typed, dated April 1970.
• Letter from Rafe de Crespigny, Secretary-General, International Congress, to Secretary, Royal Asiatic Society, to thank for the support and provide information regarding accommodation in Halls of residence. Typed, dated 20 April 1970.
• Letter from L.P. Elwell-Sutton to Secretary, Royal Asiatic Society, to ask to be kept informed regarding flights. Typed, dated 26 May 1970.
• Letter from Rafe de Crespigny, Secretary-General, International Congress, to Secretary, Royal Asiatic Society, to send a list of delegates. Typed, dated 8 June 1970. With this letter is an Alphabetical List of Delegates from U.K. and Ireland. Computer generated, dated 28 May 1970.
• Letter from Rafe de Crespigny, Secretary-General, International Congress, to D.W. Anthony, British Association of Orientalists, regarding the possibility of proposed shared flights. Typed, dated 10 July 1970.
• Correspondence between Henry G. Schwarz and Secretary, Royal Asiatic Society, concerning the possibility of affinity flights. Two letters, typed, dated 25 July - 6 August 1970.
• Letter from Professor S. Morag to Dr Anthony concerning the possibility of affinity flights. Typed, dated 31 July 1970.
• Correspondence between Professor J. Aquilina and Secretary, Royal Asiatic society, concerning affinity flights. Two letters, typed, dated 20 August-2 September 1970.
• Letter from M. Gatehouse to Secretary, Royal Asiatic Society regarding the tightened regulations for affinity flights. Typed, dated 8 September 1970.
• Correspondence between L.S. Leshnik and the Royal Asiatic society concerning the possibility of affinity or group flights. Two letters, typed, dated 16 November - 27 November 1970.
• Correspondence between Louis Allen and Royal Asiatic Society regarding affinity flights. Two letters, typed, dated 23 November - 27 November 1970.
• Correspondence between Professor S. Morag and the Secretary, Royal Asiatic Society, concerning the possibility of affinity flights and that one would not be happening. Two letters, handwritten and typed, dated 30 November - 29 December 1970.

There is further correspondence with W.F. & R.K. Swan (Hellenic Ltd.), Qantas, Kearsley Travel, Thomas Cook and Son Ltd., and Trans-Australia Airlines regarding the possibilities of organising an affinity flight. Nine items, typed, dated 8 June - 13 November 1970.

Correspondence regarding the drinking horn is:

• Letter from Mary Hutchinson, the Australian National University, to Miss Crawford, Secretary, Royal Asiatic Society, to ask on behalf of Professor Basham the whereabouts of the drinking horn and whether it might be possible for it to be present at the Canberra Congress. Typed, dated 27 October 1970.
• Letter from Sun Alliance & London Insurance Group to confirm that the drinking horn will be insured whilst in transit to Canberra. Typed, dated 11 December 1970.
• Letter from Miss Crawford, Secretary, Royal Asiatic Society, to Mary Hutchinson, the Australian National University, to inform that the drinking horn is at the Royal Asiatic society and that Professor E.H.S. Simmonds will be bringing it to the Congress. Typed, dated 14 December 1970.
• Insurance policy from The Westminster Fire Office for the drinking horn. Printed with typed inserts, dated 15 December 1970.
• Statement from B.W. Robinson to state that the drinking horn is being taken by Simmonds to the Congress and will be returned to the United Kingdom afterwards. Typed, dated 16 December 1970.
• Letter from Secretary, Royal Asiatic Society, to Sun Alliance & London Assurance Group to enclose a cheque to cover the insurance of the drinking horn. Typed, dated 21 December 1970

For the 30th Congress the title was changed to the International Congress of Human Sciences in Asia and North Africa. The Congress was held in Mexico City in August 1976. Material concerned with this Congress is: * Letter from Marion Evans, Superintendent, Congress & Inclusive Tours, Lufthansa, to send the preliminary announcement and poster for the 30th International Congress of Human Sciences in Asia and North Africa. Typed, dated 11 March 1975.

• First Invitation to the Congress giving details of the sections, papers, trips and registration. Printed in Spanish, English and French, undated.
• Poster for the 30th Congress. Printed in Spanish, English and French, undated.
• Letters from Sabena Airlines and CP Air to the Royal Asiatic Society offering assistance in travel arrangements to the Congress. Two letters, typed, dated 20-23 May 1975.
• Letter from Jorge Alberto Lozoya, Secretary General, 30th Congress, to Royal Asiatic Society to ask whether the Society would assist in coordinating travel for groups of scholars to the Congress. Typed, dated 14 November 1975.
• Provisional Registration Form for the Congress. Printed in Spanish, English and French, undated, with accompanying envelope.
• Correspondence between Mrs J. Makowiecka and Mrs Crawford, Secretary, Royal Asiatic Society, concerning the contact details for the 30th Congress. Two letters, handwritten and typed, dated 11-15 December 1975.
• Correspondence between Dr J.G. de Casparis and Mrs Crawford, Secretary, Royal Asiatic Society, concerning Casparis being the Society's official representative at the Congress. Two letters, typed, dated 2-11 July 1976.
• Letter from L. Bazin, Secretary-General, International Union for Oriental and Asian Studies, to send the updated Constitution of the Union after the General Assembly held at the Mexico Congress. Typed in French with printed constitution in English and French, undated.

The Congress name was subsequently altered to the International Congress of North African and Asian Studies. The 34th Congress was held in Hong Kong in August 1993. The material associated with this Congress is:

• Correspondence between Gyorgy Hazai, Secretary-General, International Union for Oriental and Asian Studies, and A.D.H. Bivar, President, Royal Asiatic Society, concerning the Society's representation at the Congress in Hong Kong and points for the Agenda for the meeting of the Union to be held there. Two letters, dated 17 May - 2 June 1993.