The Ryukyu Kingdom (1372–1879) on Okinawa Island used various writing conventions, all of which were markedly different from spoken registers. A unique feature of Ryūkyū's writing conventions is that in the Old Ryūkyū period (?–1609), it developed a predominantly kana writing convention that was based on sōrō-style Written Japanese but exhibited heavy Okinawan influence. After the conquest by Satsuma Domain in 1609, however, this style of writing was replaced by standard sōrō-style Japanese that was written predominantly with kanji. Other than that, Okinawan features were confined to the recordings of songs to sing, poems to read aloud, and plays to perform verbally, and did not have an autonomous status as literary writing. Instead, the samurai class of the kingdom was aligned with the literary tradition of mainland Japan that was established during the Heian period. Predominantly kana writings of Old Ryūkyū It is not clear when and how writing systems were introduced to Okinawa Island. Modern scholars generally speculate that Zen Buddhist monks brought kana from mainland Japan to Okinawa Island. During the Muromachi period, Zen monks worked as translators, diplomats and political advisers using a network of temples that was centered in Kyoto and was extended to Okinawa Island. Writings they left on Okinawa Island in the 15th century were mostly Classical Chinese (Kanbun) stone inscriptions, but a stone epitaph was written with kana. In the 16th century, a new style of stone inscriptions emerged, with Kanbun on one side and sōrō-style Japanese on another side. This style of writing is noted for heavy linguistic interference from Okinawan. An example of this style is the Sōgen-ji geba-hi (1527), which reads: The first part of the inscription, anji mo gesu mo, is a characteristically Okinawan phrase. The word kuma (this place) is an Okinawan word that corresponds to Standard Japanese koko. Verbs, in addition to nominals, exhibit Okinawan characteristics. The verb oreru was chosen instead of the Written Japanese form oriru, and it regularly corresponds to the modern Shuri speech form /uriyun/. At the same time, however, this inscription exhibits non-Okinawan features. The Okinawans would have used wote (modern Shuri speech: /wuti/) as the locative marker, but the standard form ni te was used in the inscription. The obligation marker beshi at the end of the sentence is another Written Japanese feature that was borrowed into the Shuri variety but remains rare. Overall, the Okinawan influence is so heavy that