The district was born from a larger reshuffling. In 1910, Belgian administrators combined parts of the Stanley Falls and Lualaba districts to form Katanga - not yet a formal district but a vice-government general, a category that allowed concentrated military and administrative attention to be paid to the mineral-rich south. Two years later, the arrete royal of 28 March 1912 subdivided the colony into 22 districts. The map shows Tanganika-Moero bordered by British territories and Lake Tanganyika to the east, Kivu and Maniema districts to the north, Lomami and Lulua districts to the west, and Haut-Luapula District to the south. In 1913, Katanga itself became a formal vice-government containing the districts of Lomami, Tanganika-Moero, Lulua, and Haut-Luapula. The logic was practical. Belgian colonial policy in Katanga was driven by copper mining at what is now Lubumbashi, and the administration needed enough districts to supervise labor recruitment, tax collection, and security across a territory the size of Western Europe.

The Luba-Katanga, the Bemba, the Hemba, the Tabwa, the Tumbwe, the Lwalu, the Sanga, and many other peoples lived within the district boundaries. The colonial administration imposed categories - 'districts,' 'territories,' 'sectors' - that had little to do with how communities actually organized themselves. Labor policy was often coercive. The copper mines at Elisabethville (now Lubumbashi) drew workers from across the district, some recruited voluntarily, many under pressure. The Force Publique, the colonial army, maintained order with methods that ranged from ordinary policing to brutal punishment. For most people in the district, the word 'Tanganika-Moero' would have meant nothing. What they experienced was a colonial administrator who arrived every few years, taxes payable in labor or cash, and a distant lake that sometimes brought missionaries or traders upriver.

By 1933, Belgian authorities had concluded that their original 22-district framework was too decentralized. The colony was reorganized into six provinces, named after their capitals, with the central government assuming more direct control. The number of districts dropped from 22 to 15, subdivided into 102 territories. Katanga became Elisabethville Province. Tanganika-Moero was dissolved. Its northern half became the new Tanganika District. Its southern half was absorbed by the Haut-Katanga District, centered on the copper-mining region around the provincial capital. The name Tanganika-Moero disappeared from the map, surviving only in administrative records and in the decorative maps of a 1950 Atlas General du Congo that colonial geographers produced as the Belgian era entered its final decade.

The story doesn't end in 1933. On 11 July 1960, Katanga seceded as an independent state under Moise Tshombe, days after Congolese independence, plunging the region into the Katanga Crisis. In November 1961, the UN and central government retook the northern portion and made it the province of Nord-Katanga. On 21 January 1963, the remainder was divided into Lualaba and Katanga Oriental. On 28 December 1966, under Mobutu Sese Seko, all three were merged back into a restored Katanga Province. That arrangement lasted until 2015, when the administrative map was redrawn again and Katanga was split into Haut-Katanga, Haut-Lomami, Lualaba, and Tanganyika provinces. The town of Kalemie, on the shore of Lake Tanganyika, was elevated to capital of the new Tanganyika Province. The 1912 colonial district that bore Lake Tanganyika's name has found itself, in some form, resurrected more than a century after Belgian clerks first drew its lines.