mainly along the coastal tracts of Kerala (especially in major Kerala ports such as Calicut (Kozhikode), Cannanore (Kannur), Tanore (Tanur), Funan (Ponnani), Cochin (Kochi) and Quilon (Kollam)). They were traditionally elite merchants who were all part of the brisk foreign trade. Until well into the European period, the Muslims were almost exclusively concentrated in the port cities. Middle Eastern sailors had to rely on lighterage at most of the Kerala ports in the medieval period. This led them to enter into mutually beneficial relationships with the traditional sea fishermen community. A large majority of fishermen, once low-caste Hindus, in northern Kerala now follow Islam. Inland Growth After and during the Portuguese period, some of the Muslim merchants were forced to turn inland (Malabar) in search of alternative occupations to commerce. Some acquired land and became landowners and some became agricultural labourers. Between 16th and 20th centuries, the collective Mappila numbers increased rapidly in Malabar District, chiefly by the conversion among the lower and 'outcaste' Hindu groups of the South Malabar interior. The peak of the Muslim distribution in Kerala had gradually shifted to the interior Malabar District. William Logan, comparing the Census Reports of 1871 and 1881, famously concluded that within ten years some 50,000 people from the Cheruma community (former untouchables) converted to Islam. Muslim growth in the 20th century has considerably outpaced that of the general Kerala population due to higher birth rates. British distinctions During the British period the so-called Mappila Outbreaks, c. 1836–1921 led the officials to make and maintain a distinction between the interior Mappilas and the 'respectable' Mappila traders of the coastal cities, such as Calicut. The two other regional groupings are the high-status Muslim families of Cannanore in North Malabar — arguably converts from high caste Hindus — and the Muslims of Travancore and Cochin. The Colonial administrates also kept a distinction between coastal and inland Mappilas of the South Malabar. Thangals (the Sayyids) – at the top were the aristrocratic Tangals (the Sayyids), who claim descent from the family of Prophet Muhammed. Arabis - Below the Thangals are Arabis (mostly from the coastal towns), the people tracing their origin from the West Asian intermarriage with Malayali women. Landed Aristocracy - the Arabis were followed by the landed aristocracy, centred on Cannanore, North Malabar, arguably converts from high caste Hindus. Lastly, there were the converts from the Backward and Scheduled Hindu castes (such