Massive Chinese immigrations, mainly from Yan (Hebei) and Qi (Shandong), continued without cessation, implanting Chinese cultures in the peninsula. The Yan people came from Beijing via Liaodong and the Qi people came across the Yellow Sea. Among them, the Wang clan, whose ancestor is said to have fled there from Qi in the 2nd century B.C., became powerful. It is presumed that most of Lelang Chinese spoke the Yan dialect.
This is my last posting,hope I have answered your question.
李之蘭 ethnically classified as 女真族 by both Korean & Chinese sources.According to Taiwan author 王永一,there have been rumor in Chinese history academia circle for years that he was really of (宋朝)漢民族 ancestry NOT a genuine 女真系.
S Korean professor named 徐炳國 did an extensive research on 李之蘭's ( 豆蘭帖木兒 ) family background and confirmed he was indeed a descendant of Song Dynasty'd great general named 岳飛's son 霆.
* Source; book titles 青海李氏世譜,it's published in 韓国語