Lord of Soma district in Mutsu Province and the sixteenth head of the Soma clan. The Soma were a distinguished warrior family originating in Soma district, Shimousa Province, and a powerful daimyo house holding extensive territory in southern Oshu (present-day Hamadori, Fukushima Prefecture). They are also long known for preserving the tradition of Soma Nomaoi (wild horse chase). When Date Masamune began expanding rapidly, the Soma faced years of fierce aggression. Yoshitane adroitly alternated between tenacious diplomacy and combat to defend Soma independence. During Toyotomi Hideyoshi's Oshu settlement of 1590, Masamune's continued attacks on Soma territory even after a ceasefire became an issue, and Hideyoshi handed down a direct judgment. The ruling confirmed the Soma's domain and guaranteed their status as an independent daimyo house. At the Battle of Sekigahara (1600) he sided with the Eastern army and followed Tokugawa Ieyasu; in the Edo period he successfully maintained the Soma as lords of Soma-Nakamura domain at 60,000 koku. The Soma Nomaoi tradition continues to be held today in Soma City and Minamisoma City, Fukushima Prefecture.

A pragmatic strategist who skillfully combined diplomacy and military force to preserve independence against the Date juggernaut. He navigated dealings with Hideyoshi and Ieyasu, always prioritizing the survival of the Soma clan.

He established the foundation of the 60,000-koku Soma-Nakamura domain and ensured the Soma survived throughout the Edo period. The Soma Nomaoi continues today as a tradition linked to World Agricultural Heritage, and his reign contributed to its continuation.