The big distributors in Istanbul, led by İpek Film and Kemal Film, gradually expanded their distribution system throughout the rest of the country during the 1930s, leading to the so-called "regional system" (Bölge İşletmeleri), which consisted of seven distribution areas headquartered in the most significant cities in those regions: Istanbul (Marmara Region), İzmir (Aegean Region), Ankara (Middle Anatolian Region), Samsun (Black Sea Region), Adana (Mediterranean Region), Erzurum (East Anatolian Region) and Diyarbakır (South East Anatolian Region). The Regional System became much more important after the 1950s, when local film production dramatically increased and local films surpassed imported films in both ticket sales and revenues. This system became the financial foundation of Yeşilçam (often referred to as "Turkish Hollywood"), which was the heart of Turkish film production between the years 1955–1975. After 1965, a so-called "Combined System" (Kombine Sistem) led by a trust of regional leaders is said to have taken control of almost everything regarding production. A leading figure of the trust was producer Türker İnanoğlu, who is still active in the media business today, now running Ulusal Film, Turkey's largest TV production company.