Even when millet was brought by some migrants from northeast China to Korea, archaeological evidence demonstrates that the scale of migration was almost certainly not huge more than enough to lead to a fundamental linguistic change or the dispersal of the linguistic family. ^
Some of these letters were only casino site used to signify the sounds of Chinese rime tables. A few of the Korean sounds represented by these obsolete letters still exist in dialects.
There are a few exceptions, but Over-all, the pronunciation principles with the language are very simple and obvious. You won't discover tones in common Korean, so getting going with speaking is fairly easy.