Hunter-gatherers lived in South Asia as early as 2 million years ago, hunting and gathering food as they moved from place to place for various reasons such as following animal migrations and seasonal availability of plants. Archaeological evidence such as stone tools and sites near water sources provide information about these early people. Stone tools were made using two techniques - striking flakes off cores using hammerstones, or pressure flaking using bone or stone tools. Fire was in use, and traces have been found in caves. Around 12,000 years ago, environmental changes led to the development of grasslands and grain-bearing grasses, influencing early human settlement and activities. Rock paintings and engraved ostrich eggshells depict aspects of their lives and culture.