Final answer:
The Indus Valley Civilization emerged around 2600 BCE and was highly urbanized with cities such as Mohenjo-Daro and Harappa. It had advanced agriculture, social structures, and a complex writing system. The civilization declined around 1700 BCE, possibly due to environmental factors, before the region was influenced by the migration of Aryans.
Step-by-step explanation:
The settled cultures of the Indus Valley Civilization began to emerge in what is now modern-day India and Pakistan around 2600 BCE. This civilization developed great urban centers such as Mohenjo-Daro and Harappa, with populations that could range from 30,000 to 60,000 inhabitants. These cities were built on an agricultural foundation, mainly focusing on crops like wheat, barley, and millet, which allowed for the development of stable, sedentary societies. Such an advanced level of social organization also gave rise to complex religious and civil structures. During the same period, religious traditions such as Hinduism began to take shape around 2000 BCE, eventually leading to other significant religions such as Buddhism in the fifth century BCE.
By 2000 BCE, the Indus Valley was profoundly urbanized, encompassing several large cities as well as approximately a thousand smaller urban areas. The civilization is notable for its high levels of organization, sophisticated urban planning, and complex writing system known as the Indus script. However, around 1700 BCE, the advanced urban settlements began to be abandoned, possibly due to environmental changes, leading to the eventual decline of this early civilization. Following this period, the region was influenced by the migration of the Aryans, who introduced the social framework of hereditary castes and the Vedic religion, which evolved into Hinduism. The Indus Valley Civilization's mysterious decline has intrigued historians and archaeologists, who, to this day, strive to solve many unanswered questions about this ancient society.