With the emergence of the Japanese camera industry, mainly a consequence of the US pressure on West Germany's Zeiss to cease collaboration with the East-German Zeiss, and also the lack of raw materials the former was enduring, it was in a way forced to form an alliance with a Japanese maker. Asahi, maker of the Pentax, was engaged first; and it went as far as Zeiss designing a common lens mount, which constituted a detour from Pentax's adoption of the East German M42 mount, named for many years as the "Pentax Mount" to avoid any accreditation to the Eastern Bloc, and which became the Pentax K-mount after the two firms parted company. An alliance was then formed with Yashica, and a new line of Contax single-lens reflex cameras was born, starting from the RTS of 1975. Numerous models followed, which also included compacts, medium-format reflex cameras, and digital cameras.