Legnica (archaic Polish: Lignica, German: Liegnitz, Czech: Lehnice, Latin: Lignitium) is a city in southwestern Poland, in the central part of Lower Silesia, on the Kaczawa River (left tributary of the Oder) and the Czarna Woda. Between 1 June 1975 and 31 December 1998 Legnica was the capital of the Legnica Voivodeship. It is currently the seat of the county and since 1992 the city has been the seat of a Diocese. As of 2012, Legnica had a population of 102,708 inhabitants. The city was first referenced in chronicles dating from the year 1004, although previous settlements could be traced back to the 7th century. The name "Legnica" was mentioned in 1149 under High Duke of Poland Bolesław IV the Curly. Legnica was most likely the seat of Bolesław and it became the residence of the High Dukes that ruled the Duchy of Legnica from 1248 until 1675, when it was inherited by the Habsburgs after the death of George William of Silesia. Legnica became renowned for the fierce battle that took place at Legnickie Pole near the city on 9 April 1241 during the Mongol invasion of Europe. The Christian coalition under the command of the Polish Duke Henry II the Pious, supported by nobles, knights, and mercenaries, was decisively defeated by the Mongols. This, however, was a turning point in the war as the Mongols, having killed Henry II, halted their advance into Europe and retreated to Hungary through Moravia. During the Renaissance period, Legnica was one of the most important cities of Central Europe, having a population of nearly 16,000 inhabitants. The city began to rapidly develop after the sudden discovery of gold in the Kaczawa River between Legnica and the town of Złotoryja. In 1742 the city was annexed by the Kingdom of Prussia after King Frederick the Great's victory over Austria in the War of the Austrian Succession. It remained in Germany until the end of World War II, when and all of Silesia, east of the Neisse (Nysa), was transferred to Poland following the Potsdam Conference in 1945. Legnica is an economic, cultural and academic centre in Lower Silesia, together with Wrocław. The city is renowned for its varied architecture, spanning from early medieval to modern period, and its preserved Old Town with the Piast Castle, one of the largest in Poland. According to the Foreign direct investment ranking (FDI) from 2016, Legnica is one of the most progressive high-income cities in the Silesian region.