Choose the correct option.
Moscow was first mentioned in chronicles in 1147. It was a small ... in Rostovsko-Suzdalskoye Principality and didn't play any ... role at that time. Prince Yury Dolgoruky, who is considered the ... of Moscow, constructed a series of fortifications along the left bank of the Moskva River. These original structures were the ... of the Kremlin. In the 14th century, Moscow Prince Ivan Kalita was appointed ... tax collector. He was a very clever, cruel ruler, who knew how to get what he wanted. ... his reign, Moscow became the richest principality in Russia and presented a real threat to Tatar-Mongol ... . Fifty years later, Ivan Kalita's grandson, the Grand Prince of Moscow, Dmitry Donskoy, led the united ... of many principalities and defeated the Mongol army at the Battle of Kulikovo. That was the beginning of the centralisation of Russian ... around Moscow.