Sirsa is old. It appears as Sarsuti or Sirsa in medieval accounts and sits on the dry course of the Ghaggar, on the route that ran from the Delhi country toward Bhatner and Multan. Firoz Shah Tughlaq's canal reached it. Timur passed through in 1398.
The town's speech is Bagri and Punjabi and its population is heavily Sikh, from villages settled out of Ferozepur and the Malwa on canal land in the nineteenth and twentieth centuries. The Punjabi presence in the district is why the 1966 division of Punjab was argued so hard over Sirsa and Fazilka.
The headquarters of the Dera Sacha Sauda is at Sirsa. Its head, Gurmeet Ram Rahim Singh, was convicted of rape in August 2017 and of murder in 2019. The verdict in 2017 was followed by rioting in Panchkula and elsewhere in which more than thirty people were killed.
The dera phenomenon in the Malwa, dozens of establishments with large followings drawn disproportionately from Dalit and landless communities, is one of the most significant social facts about the region and is poorly studied outside a small academic literature.
The town sits on the old Ghaggar course at the edge of the desert and its history runs back through the sultanate period as Sarsuti and Sirsa.
It went to Haryana in 1966 and its population is substantially Punjabi speaking and Sikh, which makes it one of the places where the language boundary and the state boundary do not match.
The Ghaggar bed beside it is dry for most of the year and floods badly when it is not, and the Harappan sites along that course run from here into Rajasthan.