The name of this clan originates from the three river valleys in the hills of Kangra district (Himachal Pradesh). The neighboring Punjab plain, around the ancient region of Jalandhar, was also part of their clan-state for a long time. The Trigarta warrior clan finds mention in the ancient texts, including the Mahabharat, where their Raja Susarma is minor character.
In the Ashtadhyayi of the ancient mathematician Panini, mention is made of clan-states forming confederacies, and one such Panini writes, is the Trigarta-shashta or the league of six Trigartas:
Since none of these names are found in any other text, epigraphic record, or coin, they appear to be semi-independent branches of the Trigarta clan itself. During the period of foreign invasions some of these may have shifted to Rajasthan and other places, since "Trigartas" are mentioned as warlike allies of both the Malavs and Yaudheyas in epigraphic records and texts.
In their original homeland of Kangra, the main Trigarta clan survived the Yavan invasion and struck coins in the 1st century BCE. These bear the legend: Trakata-Janapadasa. Subsequent to this period neither coins nor texts mention the Trigarta clan.
Their state probably broke-up, with the independence of the numerous Rajanya and Thakkura families, and came under the Kushan Empire. However a new monarchical state arose from the ruins, centered in the Kangra district, which eventually recovered the rest from the declining Kushans. This state, alternatively called Jalandhar and Trigarta, along with its reigning Rajas finds mention in Hieun-Tsang's travels (7th century CE) and in the Rajatarangini (5th and 9th centuries CE).
With the Islamic invasions (10th century CE) the historic name Trigarta passes out of general usage, and is replaced by the name of the famous fort that served as the state's capital. But to this day the name "Trigadh" is applied to the three streams (Banganga, Kirali, and Nayagul) that join together and flow into the River Beas.
The Kangra Fort became an important center of resistance for the Hindus, and a target for the Islamic invaders who made several attempts to capture it but were always repulsed. In the 14th century even these attacks ceased, as the power of the Delhi Sultanate waned, and the Rajas of Kangra struck coins as a sign of their independence for the next two centuries.
These Rajas and their clansmen bore the clan name Katoch, which like Trigarta, appears to have a geographical origin. In the 19th century the British historian Moorcroft noted that the Kingdom of Kangra had three provinces: Palam, Changa, and Katoch. This Katoch province centered on the fort of Kangra and the nearby rugged hills.
The re-conquest of the Trigarta clan-state into a monarchy needed a secure base from where the nascent monarchy could first emerge. This base could only be located in the Kangra district, where apart from the rugged hills the valley nestled between them, and protected by the Kangra Fort, could provide the economic resources for the rising monarchy. This could explain how the ruling clan took the surname Katoch from this region——however the exact meaning of Katoch and why it was applied to the Kangra region is still a mystery.
Interestingly the Rajas of Kangra possessed their genealogical table (vansavali) from ancient times, containing almost 500 names, starting with their founder Bhumi Chandra. If the accepted average of 20 years is applied to each reign, Bhumi Chandra would be dated to almost 8000 BCE! Of course colonial and leftist historians believe that the whole genealogy is a myth and that the Rajput clans invented such descents for glorification.
Strikingly the 234th name in this vansavali is Susharma Chandra——the name matches that of Susarama the ruler of Trigarta who was a minor character in the Mahabharat. And calculating his period by the above method brings his reign to 3320 BCE, which is close to the traditional date assigned to the Mahabharat War (3102 BCE), of course counting for reigns where a younger brother succeeded or a minor ruled for a long time.
Now the usual colonial-leftist claim that Rajput clans invented their descent from powerful ancient families, whose genealogies are mentioned in the Puranas, does not apply in this case. The genealogy of the Trigarta clan is not found in any ancient text, and even the name of this clan was forgotten at the time the Kangra State rose to power. The genealogy appears to have been preserved in the memory of their Katoch descendants to modern times.
In any case if glorification was what the Katoch clan wanted, why would they pick an unknown ancient clan, whose only noted king is a minor character in the greatest Hindu Epic, and worse, one who fights on the side of the villainous Kauravas?
Given all these facts it seems likely that the Katoch clan is descended from the ancient Trigarta warrior clan.
 Sanskrit Tri translates to three, garta translates to hollow or valley. Garta has evolved into modern Hindi's Gaddha/Khadda meaning hole.
 In fact the colonial historians, like Hutchinson and Vogel, admitted, "The general antiquity of the Kangra family is undoubted, and we may therefore conclude, that in the Vansavali, from the time of Susarma Chandra, we possibly have to do with an historical record."
 In another parallel with their Trigarta ancestors, the Katoch clan also formed independent branches named Jaswal, Guleria, Sibaia, and Dadwal, each of whom founded its own kingdom in Himachal Pradesh. Like the Trigarta Shashta these clans also formed confederacies with their parent clan against outside powers.