What is the name of the traditional regalia worn by Bill Gates in this picture?

"Babanriga", which directly translates from Hausa language as "big shirt" (sometimes spelled "Baba riga"), is a formal traditional garb or regalia popularly worn in West Africa and particularly in the Islamic northernmost parts of Nigeria, Niger and Cameroon. It is worn on formal occasions like official State or Royal functions, at religious, weddings or other traditional celebrations. It is a two piece outfit comprised collectively of an inner "kaftan" and a pair of trousers (in hausa language known collectively as "danchiki" or "danshiki"); and an outer regalia known as the babanriga. Sown usually from expensive fabrics like brocades, cottons, silks, or other African textiles like "adire" or "aso oke", they come in a variety of colors, styles and sizes. The regalia may be adorned with intricate and colorful machine or handmade designs. The average cost of a babanriga varies but may cost the equivalent of $10,000 if richly accessorized. The outfit is usually incomplete without a cap.