China has a diverse landscape ranging from tropical in the south to subarctic in the north. It has a population of over 1.3 billion people, mostly of Han ethnicity. China has over 9.6 million square kilometers of land with coastlines over 18,000 km long and borders 14 countries. Major geographic features include large mountain ranges like the Himalayas and rivers like the Yangtze and Yellow River. Though large, only 15% of China's land is arable as much is mountainous and China faces challenges of earthquakes, floods and food shortages.