My mind has been on Okinawa a lot since returning from there a few weeks ago. If time permits, I'll try to write down some of my thoughts about the trip in the coming days and post some photos, as well.
The other day, I was talking to a doctor. Although he was born near Kagoshima city and has been living in Fukuoka prefecture ever since graduating from medical school, his family originally hailed from Amami Ôshima. He told me that unlike most Japanese whose family names are written with two or three (and occasionally four) Chinese characters (e.g. 田中 - Tanaka, 清水 - Shimizu, 西後 - Saigo, 坂本 - Sakamoto, 長谷川 - Hasegawa, 長曽我部 - Chôsokabe etc.), the family names of the people of Amami Ôshima are often written with a single character (e.g. 堺 - Sakae, 中 - Atari, 元 - Hajime).
This calls for a brief history lesson.
In the late sixteenth century, Toyotomi Hideyoshi (warrior and unifier of Japan 1537-1598) asked the Ryūkyū Kingdom for help in his ill-faited attempt to conquer Korea. Hideyoshi intended to take his ambitions on to China in the event that he succeeded in Korea, but as the Ryūkyū Kingdom was a tributary state of the Ming Dynasty, Hideyoshi’s request was turned down.
Having refused demands for aid on a number of occasions, the Ryūkyū Kingdom drew the ire of the newly established Tokugawa shogunate (1603–1867) and Shimazu clan of southern Kyūshū, and in 1609 the Satsuma feudal domain (present-day Kagoshima prefecture) was given permission to invade the kingdom. While the the Ryûkyû Kingdom was able to regain some autonomy a few years later, Amami Ôshima and other islands north of present-day Okinawa were incorporated into the Satsuma domain. (Incidentally, the islands had been independent before being conquered by the Ryūkyū Kingdom in 1571.) These islands remain part of Kagoshima prefecture to this day although the inhabitants are ethnically, culturally, and linguistically—you name it—closer to Okinawa.
A side note is worth mentioning here: "The islands, by virtue of climmate, were ideal for cane cultivation, and sugar was in high demand in Osaka. To increase revenue, the domain began to reverse its agricultural policy, discouraging the cultivation of rice in favor of sugarcane. In 1746 the domain began collecting all taxes in sugar. In 1777 it established a state monopoly on sugar, making private sales punishable by death. This emphasis on sugarcane led to the most brutal aspect of the island economy: widespread slavery and indentured servitude . . . Cane cultivation was labor-intensive, dangerous, and exhausting, and the most productive farmers were plantation owners who could mobilize scores of unfree workers. By the 1800s the island elite, the district chiefs and local officials, were all slaveholders. By the mid-1800s nearly a third of the populace were yanchu, the island term for chattel slave." (From Ravina, Mark. The Last Samurai: The Life and Battles of Saigō Takamori. Hoboken: Wiley, 2004, p.83.)
As was the case for ordinary people in Japan proper, the people of Amami did not have family names until the islands came under the control of the Ryûkyû Kingdom. Family names may have been used in order to keep track of who was entering and leaving the kingdom. During the time that the islands were under the control of the Satsuma han (feudal domain), the residents were classified as farmers under the four occupations social class structure and not permitted to have names. The surnames that survive today were assigned after the fall of the feudal system and Meiji restoration in the late 1860s.
Now there was an exception to certain residents of Amami who had made great contributions to the Satsuma rule. These people, however, were given family names that consisted of one character. One purpose in doing so was to draw a distinction between people from Satsuma and those from the islands. Another reason was that as a tributary of China, the Ryūkyū Kingdom had used Chinese surnames (known as karana, 唐名. lit. “Chinese name”), and assigning such surnames was a way of acknowledging the historical connection to Ryūkyū. (Don’t quote me on this as I’m merely summarizing what others have written in Japanese.)
At the beginning of the Meiji era (1875), all Japanese citizens were required to have family names and the people of Amami tended to choose one-character names that they were familiar with. For a list of these names visit here.