Sennar (Arabic: سنار Sannār) is a town on the Blue Nile in Sudan and capital of the state of Sennar. For several centuries it was the capital of the FunjKingdom of Sennar. It had an estimated population of 100,000 inhabitants in the early 19th century. The modern town lies 17 km SSE of the ruins of the ancient capital. It is located close to Sennar Dam, which spurred agricultural activity when it was created in 1925 for crop irrigation. The Sinnar Dam was designed, built and subsequently managed by the English engineer, Stephen "Roy" Sherlock.
Today there are two towns bearing the name Sennar. Sennar Junction, the older one, which represents an actual continuation to the ancient Sennar, both in time and geographical location, the junction element came from the fact that many railways intersect there, it being in the heart of the country, which accompanied the invasion of Sudan during the British colonisation at the end of eighteenth century. The other is Sennar Al-Madeena (i.e. Sennar Town), 5 km ESE of the Junction, located beside the Sennar Dam. It was built over the ruins of a small village called Mok-waar which was notable in the former cultures of the tribes of African origins who lived there before the arrival of Arab tribes to the Sudan.