Piano concertos by Wolfgang Amadeus Mozart it was probably J.C. Bach, whom Mozart admired, who introduced the structural innovation of allowing the keyboard to introduce new thematic material in its first entry. Concertos Nos 1–4 (K. 37, 39, 40 and 41) are orchestral and keyboard arrangements of sonata movements by other composers. The next three concertos (K. 107/1, 2 and 3), which are not numbered, are arrangements of piano sonatas by J.C. Bach (Op 5. Nos. 2, 3, and 4, all composed by 1766). Based on handwriting analysis of the autographs they are believed to date from 1771–72. Concerto No. 5, K. 175 from 1773 was
Brandenburg the Province of Brandenburg, again subdivided into the government regions of Frankfurt and Potsdam. In 1881, the City of Berlin was separated from the Province of Brandenburg. However, industrial towns ringing Berlin lay within Brandenburg, and the growth of the region's industrial economy brought an increase in the population of the province. The Province of Brandenburg had an area of and a population of 2.6 million (1925). After World War II, the Neumark, the part of Brandenburg east of the Oder–Neisse line, was transferred to Poland; and its native German population expelled. The remainder of the province became a state