Final answer:
Between 4500-4000 BCE, people in the Indus valley were beginning to use bronze for various purposes.
Step-by-step explanation:
Between 4500-4000 BCE, people in the Indus valley were beginning to use bronze for tools, weapons, and adornment. This was a period when many regions of the world were transitioning from the Stone Age to the Bronze Age, and civilizations were learning to mix copper and tin to create bronze. The Indus valley, known for the Harappan civilization, was one of the great civilizations of the Bronze Age. They had access to natural resources like the fertile plains and water from the Indus River, and they were adept in urban planning and trade practices that probably included the exchange of materials like tin, necessary for the manufacture of bronze, with civilizations like Mesopotamia.