What is the theme in When China Ruled the Seas: The Treasure Fleet of the Dragon Throne, 1405-1433 by Louise Levathes?

Early Chinese interest in the sea is a theme of this book. Around 1600 B.C., the Yi peoples of eastern and southern China lived in tribes on the coastal region of China. They were separated from the fertile inland regions by mountain rangers. Without the ability to farm, these peoples were forced to turn to the sea for their livelihood. The Yi thus began a long tradition of seafaring Chinese. At the height of the last ice age, 50,000 years ago, China was linked by land with Taiwan, Java and other nearby countries. The abundance of land created an influx of immigrants from other regions of China due to the easy access to the other countries via narrow waterways. These migrants are sometimes referred to as the first "boat people."