The history of Gujarat, began with settlements of the Indus Valley Civilisation that have been found in the region. With the discovery of large Harappan site of Dholavira in Kutchh District, the history of Gujarat dates back to 5000 BC. Lothal (early Harappan town dating back to 3000 BC) has been established as the oldest known port of the world. Gujarat's coastal cities, chiefly Bharuch, served as ports and trading centers in the Nanda, Maurya, Satavahana and Gupta empires as well as Western Kshatrapas period. After the fall of the Gupta empire in the 6th century, Gujarat flourished as an independent Hindu/Buddhist states. The Maitraka dynasty, descended from a Gupta general, ruled from the 6th to the 8th centuries from their capital at Vallabhi, although they were ruled briefly by Harsha during the 7th century. The Arab rulers of Sindh sacked Vallabhi in 770, bringing the Maitraka dynasty to an end. The Gurjara-Pratihara Empire ruled Gujarat after from the 8th to 10th centuries. As well as, for some periods the region came under the control of Rashtrakuta Empire and Pala Empire. In 775 the first Parsi (Zoroastrian) refugees arrived in Gujarat from Iran.