Perak's highest population density is mainly concentrated in the coastal and lowland areas. The Chinese and Indian population represents a higher percentage of the state's total population than in the neighbouring northern Malay states. The presence of these groups was particularly significant after the British opened many tin mines and extensive rubber plantations in the mid-19th century. More than half of Perak's inhabitants in the 1930s were Chinese immigrants. Perak's Indian community is mostly of Tamil ethnicity, although it also includes other South Indian communities such as the Malayalees, principally in Sitiawan, Sungai Siput, Trolak and Kuala Kangsar; the Telugus, in Teluk Intan and Bagan Datuk; and the Sikhs, scattered in and around Perak, predominantly in Ipoh and Tanjung Tualang.