In the second half of the 3rd century Lazika Kingdom, which had been under protection of Rome, caused the conflict of the Empire and the barbaric tribes of Northern Black Sea Coast. In 257 Lazis along with the Roman garrison managed to escape the attack of Goths, but in the end of the 3rd century, during the reign of Emperor Diocletian's (284-305) another great expedition was carried out by Meotic tribes to the eastern coast of the Black Sea. The campaign was mainly aimed at Lazika Kingdom and the Ponto Province. In 291 nomadic Sarmates conquered Lazika, rushed into Ponto and reached the river Halis. Finally the Romans forced Sarmates to return to Bosfore. It is supposed that by that time there were no Roman garrisons in Lazika and it was under the influence of the Empire just formally. But on the basis of analysis of the written sources and archeological material it is established that during Diocletian's reign Lazika was under the influence of Rome not only formally but also actually.