I knocked together a few tidbits from Wikipedia for quick and easy reference:
Tsushima's rulers
It's a bit complicated:
- Up until the middle of the 13th century, Tsushima was ruled by the Abiru clan. Abiru Yajiro, the adopted son introduced at Ep2, 03:50, was from this clan.
- At the time of the Mongol invasions, Tsushima was officially ruled by the Shouni clan. The Shouni claimed descent from the Fujiwara, the most prestigious of Japan's aristocratic families. The Fujiwara were closely related to the Imperial family, due to a series of arranged marriages.
- But the high-ranking members of the Shouni who "ruled" Tsushima were actually based in Kyushu, as was the case with Shouni Kagesuke (Ep2, 08:36). It was their retainers, the Sou clan, who were the de facto administrators of the island. Sou Sukekuni, the aged chieftan who died in this episode, was of this clan. The emblem, or
mon, of the Sou clan, was pictured in the opening seconds of the first episode.
- As Sou Sukekuni said, the Sou were indeed descended from the Taira (which explains why he was able to present the armour of Taira Tomomori to Kuchii at 17:52). The Taira were one of the two major clans that fought the Gempei War in the late 12th century. They eventually lost to the Minamoto clan, who went on to establish the Kamakura Shogunate. Both the Taira and Minamoto descended from the Fujiwara.
- The Taira were mainly based in Western Japan, while the Minamoto were mainly based in the east, hence Princess Teruhi's derogatory opinion of Kuchii as an "eastern barbarian" at Ep2, 11:48. Even as far back as the 13th century, there was already a socio-cultural divide between east and west, with Eastern Japan regarded as wild backcountry, in contrast to the sophisticated capital of Kyoto, and the commercial centres of the west.
- It's said, though, that the Minamoto were the better warriors, and Minamoto Yoshitsune (whose supposed "blade" was presented to Kuchii at 09:30) was the most famous warrior among them. Yoshitsune is the subject of countless popular stories, including in manga and anime, and he's especially remembered for defeating Benkei, the warrior monk, who then became his retainer.
- The Minamoto were the first Shoguns to become de facto rulers of the nation. So, by tradition, all future Shoguns had to be able to trace their lineage to the Minamoto. The Hojo family were not related to the Minamoto, so they took a leaf from the Fujiwara playbook, and seized control as regents to the Shogun, through another series of political marriages. As I mentioned earlier, the Hojo were the true power behind the "throne" at this point in Japan's history.
Tsushima's economy and fauna
- Tsushima does not appear to have enough arable land to sustain large-scale agriculture. The population survived and prospered mainly on fishing and maritime commerce between Korea and Japan.
- Just as Iriomote island in the Okinawa/Ryukyu archipelago has the Iriomote cat, Tsushima has its own native species of wildcat, known as the
Tsushima Leopard Cat. If you watch closely in Ep2, you'd notice it at 12:47 and 15:40. It's also in the OP.