The Jats were probably the first people of Pakistan who came in contact with Islam. A number of Jats accepted Islam during the caliphate of Hazrat Abu Bakr or Hazrat Umar when they joined the Sasanian Empire in Battle of Chains 634 AD against Rashidun Caliphate.

After the victory of Muslims against the Persians under the leadership of Hazrat Khalid bin Waleed, Jats were captured and became prisoners. But after their conditions met they accepted Islam and joined Rashidun forces.

As per Tabari, Hazrat Ali during his caliphate had also deployed Jats to guard Basra's public treasury. Some sources also indicate that a number of Jats fought against Romans in Syria during the reign of Hazrat Muawiyah.

Buddhist Jats also had a role in Islamic conquest of Al-Sindh, the today's Pakistan. Because of under the rule of Brahmin dynasty Jats were not treated equally. They were forced to go out bare footed and bare headed along with dogs for their identification.

Thousands of Jats aided Arab forces and welcomed them against Raja Dahir. Apart from the Arabs, Jats were also one of the first people in world to convert to Islam.

References:

Tareekh-e-Sind, Part I by Ijazul Haq Quddusi

The People And The Land of Sindh by Ahmed Abdullah

Studies in the Foreign Relations of India, from the Earliest Times to 1947: Prof. H. K. Sherwani Felicitation Volume

The Jats: Their Role & Contribution to the Socio-economic Life and Polity of North & North-west India, Volume 2

(This thread hasn't any mean to spread hate)