Ancient Tamil grammatical works Tholkappiyam, the Ten Idylls Pathuppāṭṭu, and the Eight Anthologies Eṭṭuttokai sheds light on early religion of ancient Tamil people. Murugan was glorified as, "the red god seated on the blue peacock, who is ever young and resplendent," as "the favored god of the Tamils." Shiva was also seen as the supreme God. Early iconography of Murugan and Shiva and their association with native flora and fauna goes back to Indus Valley Civilization. The Sangam landscape was classified into five categories, "thinais", based on the mood, the season and the land. Tolkappiyam, mentions that each of these "thinai" had an associated deity such Seyyon in "Kurinji"—the hills, Maayon in "Mullai"—the forests, Kotravai in "Pālai"—the deserts, Ventan/Senon in "Marutham"—the plains and Varunan/Kadalon in "Neithal"—the coasts and the seas.