sentences:  Provision of weapons and ammunition from abroad to the Circassians caused a diplomatic conflict between the Russian Empire and the British Empire that occurred in 1836 over the mission of the "Vixen".The Russians had no detailed knowledge of the area until Baron Feodor Tornau investigated the coastal route from Gelendzhik to Gagra, and across the mountains to Kabarda, in the 1830s.In 1838, the fort of Alexandria, renamed Navaginsky a year later, was founded at the mouth of the Sochi River as part of the Black Sea coastal line, a chain of seventeen fortifications set up to protect the area from recurring Circassian resistance.