Geologists study Earth’s materials and processes. Palaeontologists study ancient life through fossils. Anthropologists study human societies and cultures. Archaeologists investigate material traces of people, such as buildings, tools and pottery. Their work can overlap and support one another.

Where an object was found, its layer and nearby remains may matter as much as its appearance. Historians also work with language experts, scientists and epigraphists, who study inscriptions. A careful record is more useful than removing an interesting object from a site.

The Gregorian calendar is widely used for civil dates. Other calendars, including Hindu, Muslim, Jewish and Chinese calendars, are also used. A festival may have a different Gregorian date each year because its date follows another calendar’s rules.

Many Indian calendar traditions use movements of the Sun and Moon. A panchanga gives calendar and astronomical information, including festival timings and predicted eclipses. Different entries answer different questions; a weather prediction is not the same kind of calculation as the timing of an eclipse.

Some hamlets grew into villages; some villages later grew into towns. Communities exchanged food, clothing, tools and other goods. Pottery supported making and storing things, while metalworking added new materials for tools and ornaments. These changes did not happen at one speed everywhere.

Communities organised work and shared needs in different ways. The chapter gives a broad picture of cooperation and leadership. Evidence is limited, so we should not turn it into a universal claim that every settlement had identical leaders or ownership rules. History develops by asking further questions.