India's First Railway Zone was Southern Railways in Chennai and oldest zone established on 14th April 1951.
This Zone was formed by combining 3 state railways:-Madras, Southern and Maharatta Railways, , South Indian Railways and Mysore State Railway.
It was part of the first six zones officially formed shortly after the nationalization of Indian Railways.
Later Central Railway zone was formed.
Southern Railways Covers Kerala, Tamilnadu and Union Territory Like Pondicherry.
Total 6 division under this zone, only 2 division was in Kerala, Trivandrum and Palakkad.