1812
.おくえぞや仏法わたる花も咲
oku ezo ya buppô wataru hana mo saku
spreading as far
as Hokkaido...
Buddha's law and blossoms
Ezo refers to the Ainu people. "Deep Ezo" (oku ezo) comprises the island of Hokkaido and other islands to the north; see Kogo dai jiten (Shogakukan 1983) 241. Issa is celebrating Buddhism's spread all the way to the northern "barbarian" islands.
Shinji Ogawa adds more information: "In 1779, the Japanese government started to govern the Ezo province, Hokkaido, which was inhabited by the Ainu race. The occasional contacts with Russian ships alerted the Japanese government, the Edo bakufu, of the potential threat from Russia. In 1802, a Russian envoy visited Japan, and, in the same year, the Edo bakufu opened an office in Hakodate in Hokkaido. In 1807, the government declared that the whole Ezo province belonged directly to Japan. This haiku (of 1812) reflects this history."