The two decades between 1900 and 1920 were a period of colonial consolidation. However, of the colonial powers that had divided the Somalis, only Italy developed a comprehensive administrative plan for its colony. The Italians intended to plant a colony of settlers and commercial entrepreneurs in the region between the Shabeelle and Jubba rivers in southern Somalia. The motivation was threefold: to "relieve population pressure at home," to offer the "civilizing Roman mission" to the Somalis, and to increase Italian prestige through overseas colonization. Initiated by Governor Carletti (1906-10), Italy's colonial program received further impetus by the introduction of fascist ideology and economic planning in the 1920s, particularly during the administration of Governor Cesare Maria de Vecchi de Val Cismon. Large-scale development projects were launched, including a system of plantations on which citrus fruits, primarily bananas, and sugarcane, were grown. Sugarcane fields in Giohar and numerous banana plantations around the town of Jannaale on the Shabeelle River, and at the southern mouth of the Jubba River near Chisimayu, helped transform southern Somalia's economy.

In contrast to the Italian colony, British Somaliland stayed a neglected backwater. Daunted by the diversion of substantial development funds to the suppression of the dervish insurrection and by the "wild" character of the anarchic Somali pastoralists, Britain used its colony as little more than a supplier of meat products to Aden. This policy had a tragic effect on the future unity and stability of independent Somalia. When the two former colonies merged to form the Somali Republic in 1960, the north lagged far behind the south in economic infrastructure and skilled labor. As a result, southerners gradually came to dominate the new state's economic and political life--a hegemony that bred a sense of betrayal and bitterness among northerners.