I wanted to open this thread to evaluate the notion of certain Jatt clans being endemic or specific to certain regions, areas. We could all list the clans/gotras that are only found in specific areas and are absent from others. And lets restrict ourselves to rural areas and villages only as people often travel for employment etc.
From my knowledge of Jatts in Punjab, I know of the following clans that are restricted to certain specific areas in Punjab.
Sidhu-Brar - One of the biggest Jatt clans in Punjab, they are restricted to the Malwa area (southern Punjab). Their highest concentration is found in Muktsar and Bathinda districts. This clan is virtually absent from villages of the Doaba and Majha areas. I am yet to find a a Sidhu-Brar whose village is in Amritsar/Jalandhar/Gurdaspur belt.
Bal - As opposed to the Sidhu-Brars, this clan is found in Doaba and Majha (north and central Punjab) but not in Malwa. Major concentration of villages is in districts of Amritsar and Nawanshar, Hoshiarpur.
Grewal - Another one of the biggest clans in Punjab. They are almost specifically found in Ludhiana district. This is one of the most economically progressive clans and is heavily into business activities. So much so that in Punjab they are sometimes referred to as Jatt Baniye for their busines acumen.
The world famous Kila-Raipur Rural Olympics is organized by a Grewal family.
Sran/Sra - One of the smaller clans specific to Malwa area. Bathinda, Muktsar and Faridkot belt is where their most villages are found.
Swaich - Probably one of the smallest clans in Punjab. Found mainly in Ludhiana district, that too restricted in pockets near Samrala and Mandi Gobindgarh. I am aware of Siwach Jaat villages in Meham and near Meerut. Members from these areas can add their bits to the thread.
Dhillon, Sandhu, Gill, Mann - Amongst the biggest clans. Found all over Punjab in all three regions.
Bajwa - Mostly Majha area specifically the dist. of Amritsar and Gurdaspur. Pakistan Punjab has the biggest number of Bajwa Jatts.
This is all the info I have for Jatts in Punjab for now. Please free to add info from your own regions in Haryana, UP or Raj.