The story of Utanka found in Mahabharata p.121-2  has some similarity with the symbols found in the Asokan pillars.
Utanka had gone to the netherworld to obtain a pair of ear-rings for his master’s wife. In the netherworld Utanka saw the following:
(1) Two women at a loom weaving a piece of cloth with black and white threads said to represent night and day.
(2) A wheel, with twelve spokes, twenty-four divisions representing ‘as many lunar changes’, and furnished with three hundred spokes. The wheel was set in continual motion by six boys representing the seasons.
(3) A man wearing a black cloth who distinguished truth from untruth.
(4) While retuning he saw a horse of extraordinary size and a bull. The horse that Utanka saw was Agni, the god of fire and the bull was Airavata.
The Asokan pillar has the following features in common with what Utanka saw in the netherworld:
(1) The wheel on the pillar, which is called Dharma Chakra, has twenty-four spokes.
(2) A bull on one side of the Chakra and a horse on the other side of the Chakra.
The trio of Wheel/Dharma-Bull-Horse:
We can see a signature that is common to Utanka’s story and Asoka’s pillar. This signature has the following three components:
(1) Netherworld is known to be the abode of the dead with Yama being it’s Lord in Hindu mythology. Yama is associated with time and Dharma. The man whom Utanka saw was also associated with ‘distinguishing truth from untruth’, a qualifier for Yama. Thus we see a Wheel and Dharma associated with Utanka’s journey. The Chakra of Asoka is also associated with time (the twenty-four spokes) and Dharma.
(2) Utanka encountered a bull on his way; the Asoka pillar has a bull depicted next to the Chakra.
(3) Utanka also encountered a horse on his way; the Asoka pillar has a horse depicted next to the Chakra.
Thus it is possible that the trio of Wheel representing time and Dharma, with a bull and a horse constitute a signature that might have been carried from the Mahabharata time.
What might the bull and horse stand for? We have already compared Yama and Osiris, as the Lords of the netherworld in the respective civilisations of India and Egypt. Can that throw more light on these two animal symbols? Osiris is represented by bull and Seth is associated with horse. The Egyptians believed the world to be ‘a balance between order and chaos’, where Osiris represented order and Seth represented chaos [1,3]. Egyptians believed that this balance was very essential for existence [1,3]. Thus the trio of Wheel-Horse-Bull are more closely connected in more than one civilisation.
 Richard H Wilkinson, The Complete gods and goddesses of ancient Egypt, Thames and Hudson, London, 2003
 The Mahabharata of Krishna-Dwaipayana Vyasa, by Kisari Mohan Ganguli, Munshiram Manoharlal Publishers, 1999
 Budge, E. A. Wallis. The Gods of the Egyptians Volume 1 of 2. New York: Dover Publications, 1969 (original in 1904)