Virtually all of Southeast Asia lies between the tropics, and so there are similarities in climate as well as plant and animal life throughout the region. Temperatures are generally warm, although it is cooler in highland areas. Many sea and jungle products are unique to the region, and were therefore much desired by international traders in early times. For example, several small islands in eastern Indonesia were once the world’s only source of cloves, nutmeg, and mace. The entire region is affected by the monsoon winds, which blow regularly from the northwest and then reverse to blow from the southeast. These wind systems bring fairly predictable rainy seasons, and before steamships were invented, these wind systems also enabled traders from outside the region to arrive and leave at regular intervals. Because of this reliable wind pattern, Southeast Asia became a meeting place for trade between India and China, the two great markets of early Asia.