A strong underlying layer of Dravidian population and culture survives in Maldivian society, with a clear Tamil-Malayalam substratum in the language, which also appears in place names, kinship terms, poetry, dance, and religious beliefs. Malabari seafaring culture led to Malayali settling of the Laccadives, and the Maldives were evidently viewed as an extension of that archipelago. Some argue (from the presence of Jat, Gujjar Titles and Gotra names) that Sindhis also accounted for an early layer of migration. Seafaring from Debal began during the Indus valley civilisation. The Jatakas and Puranas show abundant evidence of this maritime trade; the use of similar traditional boat building techniques in Northwestern South Asia and the Maldives, and the presence of silver punch mark coins from both regions, gives additional weight to this. There are minor signs of Southeast Asian settlers, probably some adrift from the main group of Austronesian reed boat migrants that settled Madagascar.