The artworks from the Tehran collection that never made it to Berlin

Ever heard of Faramarz Pilaram (1937-1982)? He's a big name in Iran. Born in Tehran, his paintings integrate modernized versions of traditional calligraphy and make use of geometrical shapes. Pilaram founded an art school in Iran. This work, "Calligraphic Painting," was created in 1975 and belongs to Farah Diba Pahlavi's art collection.

Iranian painter Jalil Ziapour (1920-1999) was a key figure of modern painting in Iran. This work, called "Autumn Leaf," reveals traces of Cubism. The squares in the background are reminiscent of Persian tiles.

In Farah Diba Pahlavi's collection, western and Persian influences are juxtaposed. Andy Warhol's screenprint "The American Indian" was created in 1976, at which time Diba - the shah's wife - purchased it for her collection.

Duane Hanson (1925-1996) created true-to-life sculptures that were critical of capitalism. "Woman with a Shopping Cart," now housed in Cologne's Museum Ludwig, is one of his more famous works. The Tehran collection includes this piece, "Boxers," which depicts Muslim convert Muhammad Ali in his fight against Sonny Liston in 1965.

Mark Rothko (1903-1970) is just one of many American artists that Farah Diba Pahlavi discovered for her collection. Rothko painted "No.2 (Yellow Center)" in 1954. The fleeting, gently overlapping layers of color are combined in an unusual composition that bears the influence of French Impressionism.

Behjat Sadr (1924-2009) was also a key figure in modern painting in Iran. His works are recognizable by their characteristic use of lines. He used a knife to slice grooves into the paint. Sadr was celebrated by critics as a pioneer of conceptual painting in his home country.

American artist Jackson Pollock (1912-1956) was one of the most significant painters of the 20th century. Farah Diba Pahlavi collected his works along with those of 60 other artists from the US and Europe. She juxtaposed them with works from Iran, revealing parallel developments in the Orient and the Occident. "Mural on Indian Red Ground" is from 1950.

Mohsen Vaziri Moghaddam (born in 1924) not only made a name for himself as an artist, but also as a teacher and author. His artworks - mainly reliefs and paintings - recall the revolutionary power of Abstract Expressionism in the US. Like Jackson Pollock, he also applies paint spontaneously in creating his works. "Scratches on the Earth" is from 1963.

In October 2015, German Foreign Minister Frank-Walter Steinmeier visited the Tehran Museum of Contemporary Art together with Iran's deputy minister of culture, Ali Moradkhani. The idea of showing Farah Diba Pahlavi's collection outside of Iran for the first time was born. But plans were scrapped when artworks did not receive a permit to leave the country.