Certainly by the 13th-century, some Nairs were the rulers of small kingdoms and the Perumals had disappeared. Trade with China, which had declined for some time, began to increase once more in the 13th-century and it was during this period that two small Nair kingdoms were established. Both of these—at Kolattunad and at Vernad—contained major seaports, and they expanded by taking over the inland territory of neighbouring chieftains. Although trade with China once more went into decline in the 14th-century, it was replaced by trade with Muslim Arabs. These traders had been visiting the area for several hundred years but their activities increased to the point that a third Nair kingdom, based on the port of Calicut, became established. There were also small kingdoms at Walluvanad and Palghat, away from the coastline. This period was characterized by continuous war between these various kingdoms, and most able bodied Nair men were assigned to fight in these wars.