Shaiva-siddhanta - a profound and elaborated Religious and Philosophical Hindus system that emerged in South India (Tamil Nadu). Shaiva-siddhanta got the ambiguous status in orthodox Hinduism because of socio-caste structure rooted in medieval India and ethno-cultural dispositions between Indian South and Indian North. Social problems put their indelible marks on development and status of Shaiva-siddhanta: it is not included in the list of orthodox Hindus astika Philosophical systems/darshanas. Many of siddhantin authors belonged to shudras and untouchables; Meykandar, the author of one of the sources of this system "Sivajnanabodha" was learned shudra. "Sivajnanabodha" as a high sophisticated treatise of Indian theistic tradition (Icvaravada) resembles some opuses of Nyaya darshana especially in argumentation in favor of God's (Icvara's, Hara's) existing. Social background of Shaiva-siddhanta became the main reason not to associate it with astika darshanas. Shaiva-siddhanta seems to be the crossroad between Nigama and Agama, Indian North and Indian South, the Aryans and Dravidians, Brahmins and inferior casts.