Azur Philatélie offers you this set of stamps of the year 1960 about summer olympics (Nb 220/223).
Mint never hinged
Ruanda-Urundi is a territory of East Africa having constituted 2 districts of German East Africa, east of the Belgian Congo. In 1916, the Belgian army occupied this part of German East Africa while the rest was occupied by the British. In 1924, the S.D.N. entrusted a mandate to Belgium.
Belgian trusteeship continued until independence in 1962 when the territory was separated into two countries that took the names of Rwanda and Burundi. After 1961, Rwanda and Burundi issued their own stamps.