The descendants of these Muslim people became known as the Lebbais and their main settlement was the town of Kayal, a presence which was noted by Vasco da Gama and Duarte Barbosa by the early sixteenth century. There is some ambiguity regarding this town: there was a harbour on the Tamraparani River in Pandyan times which was known as Korkai and when the river at this point became too silted to use (it is situated approximately 8 km inland nowadays), it was replaced by a port called Kayal, thought to be situated variously either at the mouth of the river or at the village of Palayakayal which was 4 km downstream of Korkai but is itself nowadays about 3 km inland. Marco Polo described Kayal as a bustling port and the centre of the pearl trade in 1292 but by the mid-16th century this too had probably ceased to operate and was replaced by another port, Punnaikayal ("new Kayal") under the influence of the Portuguese colonists. Punnaikayal was again at the mouth of the river, which as part of an estuary was under constant change, around 4 km from Palayakayal. It is difficult to determine with any consistency which of these locations is being referred to at various times by various authors but what does appear to be a common factor is that this was until modern times a major port for the pearl trade. "Kayal" is the Tamil word for a backwater.