Explanation:

Sangam poems help us understand the social formation of the time. According to the thinai concept, Tamilagam was divided into five landscapes or eco-regions namely Kurinji, Marutam, Mullai, Neytal and Palai. Each region had distinct characteristics –a presiding deity, people and cultural life according to the environmental conditions, as follows:

• Kurinji: hilly region: hunting and gathering
• Marutham: riverine tract: agriculture using plough and irrigation.
• Mullai: forested region: pastoralism combined with shifting cultivation
• Neythal: coastal land: fishing and salt making.
• Palai: parched land. Unsuitable for cultivation and hence people took to cattle lifting and robbery.

Source: Tamil Nadu State Board Class 11