There has been much discussion of the extent of influence from Achaemenid Persia, where the column capitals supporting the roofs at Persepolis have similarities, and the "rather cold, hieratic style" of the Sarnath Lion Capital of Ashoka especially shows "obvious Achaemenid and Sargonid influence".
India and the Achaemenid Empire had been in close contact since the Achaemenid conquest of the Indus Valley, from circa 500 BCE to 330 BCE.

Hellenistic influence has also been suggested.
In particular the abaci of some of the pillars (especially the Rampurva bull, the Sankissa elephant and the Allahabad pillar capital) use bands of motifs, like the bead and reel pattern, the ovolo, the flame palmettes, lotuses, which likely originated from Greek and Near-Eastern arts.
Such examples can also be seen in the remains of the Mauryan capital city of Pataliputra.


It has also been suggested that 6th century Greek columns such as the Sphinx of Naxos, a 12.5m Ionic column crowned by a sitted animal in the religious center of Delphi, may have been an inspiration for the pillars of Ashoka.
Many similar columns crowned by sphinxes were discovered in ancient Greece, as in Sparta, Athens or Spata, and some were used as funerary steles.
The Greek sphinx, a lion with the face of a human female, was considered as having ferocious strength, and was thought of as a guardian, often flanking the entrances to temples or royal tombs.
There has been much discussion of the extent of influence from Achaemenid Persia, where the column capitals supporting the roofs at Persepolis have similarities, and the "rather cold, hieratic style" of the Sarnath Lion Capital of Ashoka especially shows "obvious Achaemenid and Sargonid influence". India and the Achaemenid Empire had been in close contact since the Achaemenid conquest of the Indus Valley, from circa 500 BCE to 330 BCE.
Hellenistic influence has also been suggested. In particular the abaci of some of the pillars (especially the Rampurva bull, the Sankissa elephant and the Allahabad pillar capital) use bands of motifs, like the bead and reel pattern, the ovolo, the flame palmettes, lotuses, which likely originated from Greek and Near-Eastern arts. Such examples can also be seen in the remains of the Mauryan capital city of Pataliputra. 

It has also been suggested that 6th century Greek columns such as the Sphinx of Naxos, a 12.5m Ionic column crowned by a sitted animal in the religious center of Delphi, may have been an inspiration for the pillars of Ashoka. Many similar columns crowned by sphinxes were discovered in ancient Greece, as in Sparta, Athens or Spata, and some were used as funerary steles. The Greek sphinx, a lion with the face of a human female, was considered as having ferocious strength, and was thought of as a guardian, often flanking the entrances to temples or royal tombs.
Pillars of Ashoka