Sastha, the ruler of the land, is a popular deity in South India (especially in Tamil Nadu, Kerala and parts of Karnataka) and Sri Lanka. Sastha is also known as Hariharaputra, Aiyanar, Arya and Ayappan. Every one of these names has a story and religious practices built around it.
Hai Hara Putra means the son (putra) of Hari (Vishnu) and Hara(Siva). This refers to the Samudra Manthan episode where Vishnu takes the form of a bewitching woman, Mohini, to distract the Asuras who were vying with the Gods for the Amrita (Nectar of immortality). Siva was also enchanted by Mohini and out of their union Hariharaputra was born.
Aiyanar refers to the Guardian deity protecting villages in Tamil Nadu. Aiyanar is normally shown with a sword/a shield or bow/arrow riding a horse or an elephant. Please see the blog on Aiyanar for another example.
In South Coastal Karnataka and Kerala in all the Vishnu and Siva temples, there is a sanctum for Sastha in the South-West corner. Whereas the Aiyanar shrines are standalone and are normally found at the border of villages. Sastha worship rituals follow Agamic practices and Aiyanar worship is non-Agamic. However, Sastha and Aiyanar are considered different manifestations of the same deity.
For now, I will leave Arya and Ayappan out and would encourage you to look up. The book Elements of Hindu Iconography by T A Gopinath Rao is a good starting point.
Here Sastha, two-armed, is holding a Sendu (Vajradanda) in his right hand and his left hand is resting on his left knee. Sastha is seated in Virasana and a Yogapatta runs around his right side of the waist and left knee. His hair is spread out in a circle. The ornamentation is complete. Note in this case Sastha is not wearing Yajnopavitha (the sacred thread), unusual in a way. See the back view.
As is typical with Tamil Nadu bronzes, Sastha is sitting on a Padmapeetha which in turn is supported by a Bhadrapeetha.
Sastha Vigrahas in bronze with Yogapatta date back to the Chola period, around the 9th-12th century. This Vigraha is newer in comparison and may be dated to the eighteenth century but not earlier. The surface area is pitted and it has a blackish patina, suggesting prolonged periods of water immersion.
The Vigraha is about 6.5 cm in height.