There was limited economic activity besides the company-run mining, with even limited agriculture, and the city's population remained low, at approximately 39,830 by the late 1950s. As the city grew, more and more infrastructure needs required investment in roads, public works and hospitals. While several primary schools were developed for workers, until independence, there was no higher education available for the native population. Mineral wealth The area around Mbuji-Mayi is one of the richest sources of mineral wealth in the world. In the 1950s, it was estimated that the Mbuji-Mayi area had the world's most important industrial diamond deposits, containing at least 300 million karats of diamonds. The city was literally constructed on top of the diamond deposits, and while the city's reputation as a company town under tight control of Belgian economic interests meant it was neat and orderly, it also meant that the city's buildings and homes, including those of top MIBA executives, were sometimes demolished to access the diamonds. In the earlier years, most of the diamonds mined in the area came from one large MIBA-controlled mine on the city's outskirts, but diamonds could also be easily found in the area's streams and waterways, making it possible for anyone to collect them. As of 1963, Mbuji-Mayi-based MIBA was the source of 80 percent of the world's industrial diamonds and 57 percent of all diamonds. Capital city of South Kasai Mbuji-Mayi grew rapidly upon Congolese independence in 1960 with the immigration of members of the Luba ethnic group from different parts of the country. Shortly after independence, Albert Kalonji, a Luba tribal chief, declared himself ruler of the secessionist Mining State of South Kasai on Aug. 8, 1960 and established the city, then still known as Bakwanga, as his capital. In April 1961, Kalonji declared himself as emperor of the region in a traditional tribal ceremony and then returned to Bakwanga, where he was "carried through crowds of chanting, singing and cheering Balubas," and dancing continued outside his royal palace there for four days. The celebration was short-lived, as the central government's Armée Nationale Congolaise (ANC) troops took control of the town and arrested Kalonji, by December 1961. After escaping from the jail in which he was being held, he briefly re-established his government. A second assault on the independent state was launched in the summer of 1962, with ANC government troops fighting poorly armed tribesmen outside of