Explanation:

Explanation

Context-The Tamil Nadu archaeological department’s request to continue excavations at four locations, including Keeladi, has been approved by the Archaeological Survey of India (ASI).

• The development has given hope to experts that the 1000-year gap in history between the Sangam Age and the Indus civilisation may now be bridged.

Excavation sites

Keeladi

• It is located on banks of river Vaigai.It is also known as urban settlement of sangam age

Sivagalai

• Located in Tuticorin district of Tamil Nadu
• It was once known as 'Small ceylon' by Britishers.
• Evidence of Megalithic archeological remains were found in 2018.

Kodumanal

• Located in Erode district (Tamil Nadu)
• Located on river Noyyal (Tributary of cauvery)
• Flourishing ancient trade city known as Kodumanam (as inscribed in Pathitrupathu of Sangam Literature).

Adhichanallur

• Located in Thoothukudi district, TN.
• In 2004, iron-age (1500 BC to 500 BC) burial sites were unearthed by ASI from here.