Qaenat (Qahestan region) or Koohestan (mountainside) is surrounded by the desert from the south of Nayshabur right till Sistan. It has a semi-arid and temperate climate. Marco Polo in his records has named this city as ‘Tonokayn’- the combined version of the two large cities of this state i.e. ‘Toon’and ‘Qaen’.
Qaen is also called the City of Saffron because it is a major saffron producer and saffron from Qaen is prized for its unique aroma and strong colour.
The present city, which lies in a broad valley, was founded in the 15th century on the site of an ancient city. Later, the Uzbeks (a Turkic people) took possession of the city and held it until Shah Abbas I (1588-1629) expelled them. In the 18th century, Qaen fell under the control of Pashtuns which is why some of locals, though they speak Persian, still claim descent from Pashtuns rather than Persians.
There are several ancient places around the town, such as the Tomb of Bozorgmehr Qaini, 5 km to the south.
The Middle Persian work Shahrestaniha i Eranshahr mentions this city, and attributes its foundation to the legendary king Kai Lohrasp.
At least 1.567 people in Qaen and the surrounding region were killed in the 1997 Qayen earthquake.