Chapter 4 — Timeline and Sources of History

BCE stands for Before Common Era and CE stands for Common Era. CE was formerly written as AD and refers to years counted forward from the conventional date of Jesus' birth; BCE was formerly written as BC and counts backwards from that same point. For example, India's independence in 1947 is written as 1947 CE, and the approximate birth year of Gautama Buddha is written as 560 BCE.

A century is any period of 100 years. In history, centuries CE are counted every 100 years from 1 CE; we are currently in the 21st century CE, which runs from 2001 to 2100. A millennium is any period of 1,000 years; we are currently in the 3rd millennium CE, which began in 2001 CE and will go up to 3000 CE.

Because the Gregorian calendar has no year zero — year 1 CE follows directly after year 1 BCE — you cannot simply add the two numbers. Instead, add the BCE and CE values and then subtract 1. For example, if the Buddha was born in 560 BCE and the current year is 2024 CE, the calculation is 560 + 2024 − 1 = 2,583 years ago.

A timeline is a tool that shows a sequence of dates and events covering any particular period. It helps students understand the order in which historical events took place — for instance, the timeline in this chapter shows that the birth of the Buddha (560 BCE) occurred before the birth of Jesus. If the timeline were drawn at full scale from the beginning of humanity to the present, the chapter notes it would have to be almost 3 metres long.

The chapter describes four types: geologists, who study the physical features of the Earth such as soil, stones, hills, rivers and oceans; palaeontologists, who study fossils — the preserved remains of plants, animals and humans from millions of years ago; anthropologists, who study human societies and cultures from the oldest times to the present; and archaeologists, who dig up remains left behind by people, plants and animals, such as tools, pots, beads, figurines, bones and teeth.

The chapter groups sources of history into four categories: literary sources (including the Vedas and Itihasas, poems and plays, historical chronicles, manuscripts, travelogues, foreign accounts, and newspapers for recent history); archaeological sources (coins, copper plates, monuments, mounds, habitations and burials); artistic sources (paintings, pottery, toys, sculptures and panels); and oral sources (folklore and genealogical traditions). Historians try to gather information from as many of these sources as possible.

The chapter defines a fossil as an impression of footprints, or parts of plants or animals, that are found preserved within layers of soil or rocks. Palaeontologists specialize in studying such fossils, which can be millions of years old, to learn about the plants, animals and humans of the distant past.

The Gregorian calendar is the calendar now used the world over. It has 12 months adding up to 365 days, with a leap year every four years. However, century years — such as 1800, 1900, 2000 — are leap years only if they are multiples of 400; so among those three examples only 2000 is a leap year. Other calendars, such as Hindu, Muslim, Jewish and Chinese calendars, are also used alongside it for calculating festival dates.

Early humans (Homo sapiens) have existed for about 300,000 years. They lived in bands or groups, sought shelter in temporary camps, rock shelters or caves, and were mainly hunters and gatherers — relying on hunting and collecting edible plants and fruits for survival. They used fire, made stone tools such as axes, blades and arrowheads, created rock paintings found in caves all over the world, and made simple ornaments like stone or shell beads and pendants from animal teeth.

The Ice Age was a period when the Earth's climate was very cold and much of the Earth was covered with ice. The last Ice Age lasted from over 100,000 years ago to around 12,000 years ago. When the climate warmed up afterwards, the ice partly melted, swelling rivers and eventually draining into the oceans, and conditions improved for early human communities.

After the end of the last Ice Age, humans in many parts of the world began cultivating cereals and grains and domesticating animals such as cattle and goats. Communities often settled near rivers because the soil there was more fertile. Over time, hamlets grew into villages that exchanged food, clothing and tools, and new technologies such as pottery and the use of copper (and later iron) appeared.

A pañchānga is a traditional Indian book of tables that lists the days of each month along with related astronomical data. It is based on the positions of the sun and the moon and precisely predicts events like solar and lunar eclipses, times for sunrise and sunset, and weather predictions for the year. Pañchāngas are still widely used in India and also give dates and timings of festivals.

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