It is almost presumed from historical facts that some sort of group deeply related to Wakoku (such as government officials and military men dispatched by Wakoku or local powerful clans who served Wakoku) possessed certain military clout and economic interest in Gaya region (another name of Mimana); Wakoku's advance to the Korean Peninsula is recorded in history books of China and Korea as well as "Nihonshoki" (Chronicles of Japan); "Gwanggaeto Stele" tells that Wakoku subjugated Silla and Baekje; large keyhole-shaped tomb mounds, which are peculiar to the Japanese archipelago, are starting to be discovered in the Korean Peninsula; a massive amount of Japanese jade magadama (comma-shaped beads) have been excavated in the influence area of Silla, Baekje and Gaya (rare in the former territory of Goguryeo).
『日本書紀』をはじめ、中国や朝鮮の史書でも朝鮮半島への倭国の進出を示す記事が存在すること、『広開土王碑』に倭が新羅や百済を臣民としたと記されていること、またいくつもの、日本列島独特の墓制である前方後円墳が朝鮮半島で発見され始めたこと、そして新羅・百済・伽耶の勢力圏内で日本産のヒスイ製勾玉が大量に出土（高句麗の旧領では稀）したこと等の史実より、倭国と深い関連を持つ何らかの集団（倭国から派遣された官吏や軍人、倭国に臣従した在地豪族など）が伽耶地域において一定の軍事的影響力および経済的利権を有していたことはほぼ確実視されている。