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 itself promptly split up into squabbling factions and the internal situation remains precarious at best.
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 out and enter via China.
Myitsone (Mali Zup), a confluence of Mali and Nmai Rivers, a naturally splendid for hangout and fun.
There are several civil wars taking place in Northern Myanmar. Decades of landmines are still in the ground and active fighting is taking place daily (JAN 2016). Exercise extreme caution when travelling off the tourist trail, particularly to any of the border regions near China.