Tamerlane was a conqueror from Central Asia who built a large empire in the second half of the 1300's. He never set foot in Europe, and although he exchanged numerous letters with European rulers, they were mainly about military and economic matters, so he had no significant interaction with Western Civilization. Yet he became a popular figure in European legends and storytelling. Why?
The Ottoman Empire, at that time, was placing significant military pressure on Europe. It cost money, effort, and lives for the Holy Roman Empire to maintain a large defensive force on the southeastern edge of Europe. These attacks had been directed against Europe for decade upon decade, until finally the Crusades had been launched as a counter-offensive.
And then Tamerlane attacked the Ottoman Empire from the east. This meant that the Turks could not direct all their forces into invading Europe, but rather had to divert substantial assets to defend themselves against Tamerlane. This, in turn, gave Europe a little break. Hence Tamerlane's popularity in the West.
The fact that Tamerlane was a Muslim didn't stop him from attacking the Ottoman Empire, which was also Muslim. The farmers of southeastern Europe were thankful for a respite from constant incursions by Islamic soldiers, and were quite content to have the Muslims trouble each other for a while.
