No one knows exactly where oranges come from, although Southeast Asia is believed to be their first home. The ancient Greeks and Romans knew about oranges. It is possible that oranges were carried from India to Western Asia, and then to all of Europe. The Spaniards took the sour orange to the West Indies and from there to Florida, in America. Today, they are grown in most of the warmer parts of the world and are an important fresh fruit in international trade.

Identify the topic sentence of the paragraph.