Northern Myanmar is a region of Myanmar.
Kachin State has been de facto independent from central government's control since 1962, when the Kachin Independence Organization (KIO) unilaterally seceded from the Union of Myanmar. A peace deal struck in 1994 after a government army offensive made the arrangement more or less permanent, with the KIO-controlled area formalized as Kachin State Special Region #1, although KIO promptly split up into squabbling factions and the internal situation remains precarious at best.
Unlike much of predominantly Buddhist Myanmar, the Kachin people are predominantly Christian.
In Special Region #1, Mandarin will get you a lot further than Burmese (or English).
Getting in depends on where you're going. For access to government-controlled areas like the capital Myitkyina, there are direct flights from Yangon, although the adventurous may also opt to travel by train from Mandalay (24-30 hours). For the rebel-controlled north, you'll either have to battle your way through massive bureaucracy to secure permits, or take the easier way by entering via China.
Myitsone (Mali Zup), a confluence of the Mali and Nmai Rivers, a naturally splendid hangout.