Punctuation is the name for marks used in writing. They are to help understanding and correct reading. These are some common punctuation marks used in English: . is a period or full stop.
In the past, less affluent Okinawans ate sweet potatoes. Lots and lots of sweet potatoes. Rice, especially white rice, was more expensive and was a bit of a status symbol: it was something consumed only by the wealthier folks.
The capital of Okinawa is Naha, the island prefecture's capital and largest city. Its metropolitan area covers most of the southern portion of the main Okinawa Island, Naha (population 321,000) has been a port of entry for travelers and goods since the 15th century.