 Complete the following phrase:  Timur then headed west to capture the Zagros Mountains, passing through Mazandaran. During his travel through the north of Persia, he captured the then town of Tehran, which surrendered and was thus treated mercifully. He laid siege to Soltaniyeh in 1384. Khorasan revolted one year later, so Timur destroyed Isfizar, and the prisoners were cemented into the walls alive. The next year the kingdom of Sistan, under the Mihrabanid dynasty, was ravaged, and its capital at Zaranj was destroyed. Timur then returned to his capital of Samarkand, where he began planning for his Georgian campaign and 