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 Golden Horde invasion. In 1386, Timur passed through Mazandaran as he had when trying to capture the Zagros. He went near the city of Soltaniyeh, which he had previously captured but instead turned north and captured Tabriz with little resistance, along with Maragha. He ordered heavy taxation of the people, which was collected by Adil Aqa, who was also given control over Soltaniyeh. Adil was later executed because Timur suspected him of corruption.