 Under the premiership of Mohammad Daoud Khan in the 1950s, foreign investment and development increased.In 1955, the Soviet Union forwarded $100 million in credit to Afghanistan, which financed public transportation, airports, a cement factory, mechanized bakery, a five-lane highway from Kabul to the Soviet border and dams, including the Salang Pass to the north of Kabul.During the 1960s, Soviet-style microrayon housing estates were built, containing sixty blocks.