Kohtla-Järve is a city and municipality in north-eastern Estonia, founded in 1924 and incorporated as a town in 1946. The city is highly industrial, and is both a processor of oil shales and is a large producer of various petroleum products. The city is also very diverse ethnically: it contains people of over 40 ethnic groups Only 21% of the population are ethnic Estonians; most of the rest are Russians. Kohtla-Järve is the fifth-largest city in Estonia. Kohtla-Järve is unusual among municipalities of Estonia due to having a discontiguous territory. The two main parts of the city, Järve and Ahtme, both with populations around 20,000, are located about 10 km apart. Several other settlements in north-eastern Ida-Viru county, connected to oil shale mining, are administered as districts of Kohtla-Järve; the furthest, Sirgala, is 40 km east of Järve. In the Soviet time, the town of Jõhvi was also incorporated into Kohtla-Järve.