The town of Kashin was first mentioned in a Chronicle under the year of 1238, when it was sacked by the Mongols. It was given by Grand Duke Mikhail Yaroslavich as an appanage to his son Vasily, who founded a short-lived dynasty of local princes. In 1382, Kashin was annexed by the Principality of Tver.
From 1399 to 1426, it was held by a second dynasty of Kashin princes, which claimed their seniority in the house of Tver. In 1452, Kashin withstood a siege by Dmitry Shemyaka. It finally passed to Muscovy in 1486 with the rest of Tver Principality.
In 1708, the town was assigned to the Ingermanland Guberniya, and in 1719 - ro Petersburg guberniya. There are several architectural monuments in Kashin, including monasteries, churches, and cathedrals. The most ancient of these, a wooden chapel from 1646, was burnt to the ground in 1998. The town is also known as a balneological resort.
Mikhail Yaroslavich's wife Anna took the veil in Kashin's nunnery and died there on October 2, 1368. She was glorified by the Russian Orthodox Church in 1677 as a holy patroness of all women who suffer the loss of relatives. Her miracle-working relics are preserved in the Ascension Cathedral of Kashin.