The land of Jhajjar shows signs of early inhabitation. Various historical buildings can be seen here. During 1191 AD when there was a war between Gori and King Prithvi Raj, the area of Jhajjar was not inhabited and was a forest with no one living there. In the eastern part was a town by the name Malokan where the Jats lived and was amongst the worst affected areas due to the war. Most of the people living there relocated to different places after the war. Chajju Jat who was a resident of the village made an appeal so that rehabilitation of the village could be done. However the appeal was rejected by Emperor Gori. He ordered that the village should be rehabilitated somewhere else. Hence, the jats of Malokan came to live in the city of Jhajjar. After it got established, the city of Jhajjar had to go through a lot of political unrest in the hands of many rulers i.e. Mughal rulers, Muslim rulers and the Britishers too. While many people say that the city derived its name from the founder i.e. Chajju which was changed later to Jhajjar, many others are also of the opinion that it was derived from the natural fountain by the name Jharnagar. It was a part of Rohtak district until July 15th 1997, when it was separated from it.