A railway (TAZARA – Tanzania Zambia Railways) to the Tanzanian port of Dar es Salaam, completed in 1975 with Chinese assistance, reduced Zambian dependence on railway lines south to South Africa and west through an increasingly troubled Portuguese Angola. Until the completion of the railway, Zambia's major artery for imports and the critical export of copper was along the TanZam Road, running from Zambia to the port cities in Tanzania. The Tazama oil pipeline was also built from Dar es Salaam to Ndola in Zambia.