Complex sentence: The Southern African Customs Union (SACU) came into existence on December 11,1969 with the signature of the Customs Union Agreement between South Africa, Botswana, Lesotho, Namibia and Swaziland.
Split into simpler sentences: The Southern African Customs Union (SACU) is a customs union among the countries of Southern Africa. SACU came into existence on December 11,1969 with the signature of the Customs Union Agreement between Botswana, Lesotho, Namibia, South Africa, and Swaziland.