Identify the location where Buddhism originated, and give a brief account of its diffusion and current global spatial distribution.

Buddhism originated in India and is believed to have developed from the teachings of Siddhartha Gautama (born approximately 563 BCE) in Kapilavatthu near the border with Nepal. Gautama spent his life in Bihar and Uttar Pradash in eastern India. 
During the third century BCE, the Mauryan leader Ashoka converted to Buddhism and helped spread the faith by encouraging monks to travel to neighboring lands. In this manner, the faith spread from India to Sri Lanka, Burma, central Asia, Bhutan, Nepal, Tibet, China, Korea, and Japan. After Muslims entered India in the 11th century CE, Buddhism largely disappeared from India, though some historians believe it was in part absorbed into Hinduism. 
The estimates of the number of practicing Buddhists today range from 488 million to 525 million people, representing approximately 7%-8% of the world's population. China has the greatest number of Buddhists, with 244 million Buddhists. Thailand has about 64 million Buddhists, and Japan has about 45 million Buddhists. The other countries with great number of Buddhists are in Asia, including Cambodia, Laos, Sri Lanka, Bhutan, and Taiwan, among others.