In 1990 the constitution was amended to allow opposition parties, and in 1991 a new constitution provided for a multiparty system, limiting presidential powers. The MMD, now the ruling party, increased its parliamentary majority in the 1996 elections, which the UNIP boycotted. Judiciary The judicial system includes a supreme court, a high court, and lower courts modeled on the British system. African customary law is applied in special courts. In the early 1990s the armed forces of Zambia comprised an army of 20,000 and an air force of 1600.
Military service is voluntary.
Southward-migrating Bantu invaded the area that is now Zambia over a period of several centuries. The forerunners of the Sotho and Nguni groups were in Zambia before AD 1000. These early agricultural settlers and migrants developed mining and metalworking techniques. A new group, the Shona Bantu, arrived in the 12th century. Later, the Karanga clan of the Shona established the great empire of the Mwene Mutapa, which included southern Zambia.