But majority of Han Chinese in the North East migrated from Shandong right?
Yep, mostly Shandong and Hebei.
'Han' presence in the area wasn't widespread until later on during the Qing, even if the wildly vast majority of the people in Dongbei today are descendents of the late Qing-era 'settlers' or from families that are officially recognized as Han by now.
A bit into Shunzhi's reign the emperor worried that the northeast was underpopulated (PRC works highlight the scale of the fighting in the area during the late Ming and the southward flow of the ruling northeastern population into China after the Qing took over) and became concerned about the potential to make the most of its resources. So he initiated a settlement project to entice farmers from the central plains to settle in the northeast, complete with an elaborate incentive and reward system. His successor Kangxi, with the excuse that the ancestral Manchu homelands would be lost if mass scale immigration were to occur, sealed off the area with the famous 'Willow Palisades' (English?) policy. This obviously was next to impossible to enforce 100% and people trickled into the area, which eventually became easier as the Qing began to weaken. There were later bursts of immigration, especially during the 20th century, once other empires with interests in the region began to offer relatively high wages.
A key hint at the level of Chinese involvement in the area is the fact that the first Chinese records and surveys of the northeast were only written during the Qing, and produced by educated Southerners exiled to the northeast by the Qing court. The celebrated first one of these is the《绝域纪略》, written in recollection by 方拱乾 Fang Gongqian in the early 1660's after he returned home to Anhui following his exile to the Ningguta area. The book, like most that would follow through to the Republican era, was a compilation of jottings and recollections by a literate Sinophone visitor to new and strange lands. The men writing these texts (really getting into it only after the Daoguang period) would delight in describing the bizarre features of the landscape and lifestyles of the native populations, as well as in pointing out how incorrect the geography of the area as understood back home was (even if they ending up contradicting themselves on occassion). While often less than rigorously presented, these few texts are invaluable resources for providing rare glimpses into a region that we just don't have any earlier records of.
Not that there weren't any immigrants from the central plains in the area before the Qing took over Beijing. The numbers were relatively few and most likely fall short of indicating the amount of political control we usually assume that earlier central plains empires had over the northeast.
Jilin and Heilongjiang was most definitely outside of the Han Chinese orbit. But, Liaoning had always been within it. Even before China became an empire, there was a Chinese kingdom in today's Beijing and Liaoning area (Yen kingdom). How else do you think Chinese culture and genes were easily transmitted to Korea?
The problem with this (and nationalist/racialist views in general) is it needs to assume that monolithic concepts of Chineseness and Koreaness, where modern politics, written records and some weird takes on biology are supposed to be the same thing, had to be maintained for well over two thousand years. We understand this in retrospect only (otherwise, how is the northeast so closely tied to the PRC today?). Still, even with these standards, Liaoning might not make the cut.
Also, the state of Yan fell long before Han orbit existed.
