Ideal agricultural conditions, and the mastering of wet-field rice cultivation as early as the 8th century BCE, allowed villages, towns, and small kingdoms to flourish by the 1st century CE. These kingdoms (little more than collections of villages subservient to petty chieftains) evolved with their own ethnic and tribal religions. Java's hot and even temperature, abundant rain and volcanic soil, was perfect for wet rice cultivation. Such agriculture required a well-organized society, in contrast to the society based on dry-field rice, which is a much simpler form of cultivation that does not require an elaborate social structure to support it.