The main international road crossings into Tanzania are from Kenya. The most used is the border crossing at Namanga, about halfway between Nairobi and Arusha. The other principle border crossing is south of Mombasa on the coast at Lunga Lunga, from where the nearest large Tanzanian town is Tanga. There are quieter border crossings at Taveta, between Voi and Moshi, and Isebania on the main road between Kisumu and Mwanza.
Border crossings from other neighbouring countries include the Songwe border with Malawi and the Tunduma border with Zambia, both of which are in the southwestern corner of Tanzania and are reached by a good (but long) road from Dar es Salaam. There is a crossing with Uganda at Mutukulu, northwest of Bukoba, but this is a rough road and a remote region to get to. The easiest way to get to Uganda from Tanzania is via Nairobi in Kenya, from where there are daily bus services to Kampala. There is a border crossing with Rwanda at Rusomo, although again this is in the remote northwestern part of Tanzania although there are bus services between Mwanza and Kigali. Tanzania does share a border with Mozambique to the south, but road access between the two countries is very limited.
By road note:
There are many local bus companies that ply the main routes over the borders. Several companies run comfortable shuttle bus services between Nairobi and Arusha and Moshi in Tanzania. These are aimed at tourists who fly into Nairobi and are visiting the game parks in Tanzania’s northern circuit region from Arusha, or are climbing Mt Kilimanjaro from Moshi. The buses take about 5-6 hours in either direction, and drivers assist passengers with border procedures. Riverside Shuttles (www.riverside-shuttle.com) offer a reliable daily service.
For long-distance cross-border bus travel, recommended for visitors is Taqwa Bus Services (+255 655 721287, +255 655 141034, +255 715 423820), which has frequent departures to and from Tanzania and neighbouring countries. They also offer daily services between Nairobi and Kampala in Uganda, and from Dar es Salaam to Lusaka in Zambia.
Source: Tanzania Tourist Board – Plan Your Trip