Explanation: Varnas were the four main social classes in the Vedic period, which later evolved into the caste system.

Explanation: The Saraswati River was revered in Vedic texts, although its exact location is a topic of historical debate.

Explanation: The hymns of the Rigveda were composed by ancient sages known as Rishis.

Explanation: Yajurveda deals with the procedures and rituals involved in ceremonies and sacrifices.

Explanation: The Upanishads are philosophical texts that explore the concepts found in the Vedas and are associated with the later Vedic period.

Explanation: Indra was considered the chief deity during the early Vedic period, associated with thunder, rain, and war.

Explanation: The Rigveda is the oldest and most important text of the Vedic period, consisting of hymns dedicated to various deities.

The Harappan civilization was characterized by its well-planned cities and advanced infrastructure. Some of the major cities of the Harappan civilization include:

1.            Harappa: Harappa was one of the first cities to be excavated in the 1920s and gave its name to the entire civilization. It is located in present-day Pakistan and was a significant center of the ancient Indus Valley civilization.

2.            Mohenjo-Daro: Mohenjo-Daro, meaning "Mound of the Dead," is another major city of the Harappan civilization, located in present-day Pakistan. It was one of the largest and most advanced cities of its time, featuring complex urban planning and sophisticated drainage systems.

3.            Kalibangan: Kalibangan is located in present-day Rajasthan, India. It is notable for its unique fire altars and is an important archaeological site belonging to the Harappan civilization.

4.            Lothal: Lothal is situated in present-day Gujarat, India. It was a vital trading center, known for its advanced dockyards and extensive trade connections with other civilizations.

5.            Dholavira: Dholavira, located in the Rann of Kutch in present-day Gujarat, India, is known for its intricate urban planning and large water conservation systems. It is one of the five largest Harappan sites in the Indian subcontinent.

6.            Rakhigarhi: Rakhigarhi is one of the largest sites of the Harappan civilization, located in present-day Haryana, India. It is still being extensively studied by archaeologists and has provided valuable insights into the life and culture of the ancient Indus Valley people.

These cities, along with numerous smaller settlements, formed the backbone of the Harappan civilization, showcasing their advanced urban planning, architecture, and social organization.