The Kachin people organized themselves into clans and chiefdoms and were never ruled by an external power until the British colonized them. It is important to note that they were not consider the same colony as the Burmese; they were administered separately by the British.
Never until the Kachin leaders voluntarily signed the Panglong Agreement were they considered by anyone to be part of the Burmese kingdom or colony. There are large stretches of the Kachin land where, to this day, no Burmese or British person has ever stepped foot.
There is no historical pretext for the Burmese control of the Kachin land except the Panglong Agreement which the Kachin signed with the written and verbal promise of equality and autonomy within a union.
The Kachin, unlike the Burmese, fought with the allies in WWI and WWII. The Kachin rangers fought with the 101 rangers and the OSS (Pre CIA) to repel the Japanese invasion Burma and build the Stillwell, or Lido, road from India to China so supplies could reach China from Allied controlled India. Still today the US 101 rangers have contact with and support the few surviving Kachin veterans.
Wiki OSS Detachment 101
more coming soon…