It is because
(i) It was the emporium of western trade.
(ii) It was the gateway for trade and also been called the gate to Mecca because many pilgrim ships set sail from here.
(iii) Portuguese, Dutch and English had their factories and warehouses at Surat.
(iii) Textiles of Surat were famous for their gold lace borders (zari).
(v) There were magnificent buildings and innumerable pleasure parks for the comfort of the people..