Chinese Wei-Zhi 魏志倭人伝 recorded " direct " contacts between Chinese dynasties & Wa Japan earlier on.No mentioning of language & cultural & ethnicity of collective Wa-jins 倭人 related to natives of peninular statelets.I don't think they were the same people as Samhan ( 辰韓 Chinhan, 弁韓 Pyonhan, and 馬韓 Mahan ),otherwise Japanese & peninsular languages would be intelligible because modern tongue in the peninsula is derived from Silla which is 韓-based language.
According to Chinese chronicles,there was a Han-Chinese 秦朝 Qin refugee settlement in 辰韓 ( peninsula history sources also confirmed it ).Japan's 秦氏 Hata clan ( 漢系氏族 ) most probably migrated from the peninsular's 辰韓 Chinhan statelet.I suspect Japan's 東漢氏 came from 馬韓 because Baekje had a mix population included Mahan & remnant Han-Chinese of 帶方郡 ( one of Han commanderies,when Han Dynasty lost control of peninsula ).
My conclusion is those 163 漢系氏族 ( Han-Chinese family registries ) documented in Shinsen-Syoujiroku ( 新撰姓氏録 ) actually from the peninsula NOT China mainland directly.
新撰姓氏録 - Wikipedia
5世紀から秦氏、西文氏、東漢氏などが来日帰化してますし,彼らが持ってきた習俗という事で充分説明がつくと思います.彼らは征服民でなく帰化民です
Han Dynasty " influenced " the peninsula THE MOST as Tang Dynasty for Japan.
楽浪郡 Lelang was THE SOURCE of sophisticated civilization for all ancient peninsular kingdoms and Wa of Japan,then extended to peninsula's 3 Kingdoms period in concurrent with Yamato of Japan.It was like a " food chain " of cultural transfer.
Indopedia - The Indological Knowledgebase
Lelang Commandery - Wikipedia
Hyung Il Pai (1992) presented a more balanced theoretical view on Han Lelang's position in peninsula's prehistory. Basically,she argued that social and regional differentiation in the peninsula were not possible without initial Han contact. Before the Lelang period, regional differences find expression ony in terms of minor variation in pottery styles. In contrast, third-century texts of the Wei Zhi 魏志 ( 300 years after initial Han contact ) reveal the existence of various guo 国 (or tribal kingdoms) such as Puyo, Koguryo, Okcho, Eastern Ye and Samhan. They are recorded as having distinctively different social organizations, subsistence systems, customs, and rituals
The most important "traits of civilization" such as iron technology, writing, gold craftsmanship, and intesive rice agriculture, were derived from Han Lelang culture. Such widespread distribution of ideas and technology would not have been possible without the elite distribution network of seals, bronze mirrors, and luxury Han goods which stimlulated the initial exchange network.
According to Pai (1992), once this network was established in the core areas of Lelang, it quickly spread to all other parts of peninsula and into southern-western Japan, forming the "Lelang Interaction Sphere" in the peninsula prehistory that included Koguryo, Wa of Japan, and Samhan - Chinhan, Pyonhan, and Mahan.Without this initial phase, the second stage of the interaction sphere that comprised Koguryo, Paekche, Silla, and
Kofun Japan, would not have been possible. Extensive trade and diplomatic activities were heightened and reinforced by competition and warfare with Yamato Japan and peninsula's 3 kingdoms.These states shared common features in palatial architecture, in the spread of Buddhism and associated sculpture, as well as in gold artwork and jewellery.
http://www.nichibun.ac.jp/research/faculty/staff3/pai.html
http://www.eastasian.ucsb.edu/content/people_pai.html