literary language in its own right in Mawarannahr, although the Timurids were Persianate in nature. The greatest Chaghataid writer, Ali Shir Nava'i, was active in the city of Herat, now in northwestern Afghanistan, in the second half of the fifteenth century. The Timurid state quickly broke into two halves after the death of Timur. The chronic internal fighting of the Timurids attracted the attention of the Uzbek nomadic tribes living to the north of the Aral Sea. In 1501 the Uzbeks began a wholesale invasion of Mawarannahr. Uzbek period By 1510 the Uzbeks had completed their conquest of Central Asia, including the territory of the present-day Uzbekistan. Of the states they established, the most powerful, the Khanate of Bukhara, centered on the city of Bukhara. The khanate controlled Mawarannahr, especially the region of Tashkent, the Fergana Valley in the east, and northern Afghanistan. A second Uzbek state, the Khanate of Khiva was established in the oasis of Khorazm at the mouth of the Amu Darya in 1512. The Khanate of Bukhara was initially led by the energetic Shaybanid Dynasty. The Shaybanids competed against Iran, which was led by the Safavid dynasty, for the rich far-eastern territory of present-day Iran. The struggle with Iran also had a religious aspect because the Uzbeks were Sunni Muslims, and Iran was Shia.. Near the end of the sixteenth century, the Uzbek states of Bukhara and Khorazm began to weaken because of their endless wars against each other and the Persians and because of strong competition for the throne among the khans in power and their heirs. At the beginning of the seventeenth century, the Shaybanid Dynasty was replaced by the Janid Dynasty. Another factor contributing to the weakness of the Uzbek khanates in this period was the general decline of trade moving through the region. This change had begun in the previous century when ocean trade routes were established from Europe to India and China, circumventing the Silk Route. As European-dominated ocean transport expanded and some trading centers were destroyed, cities such as Bukhara, Merv, and Samarqand in the Khanate of Bukhara and Khiva and Urganch (Urgench) in Khorazm began to steadily decline. The Uzbeks' struggle with Iran also led to the cultural isolation of Central Asia from the rest of the Islamic world. In addition to these problems, the struggle with the nomads from the northern steppe continued. In the seventeenth and eighteenth