The chariot on which both friends, Sri Krsna and Arjuna,  rode was donated by Agni (the fire-god) to Arjuna, and that was indication that this chariot was capable of conquering all directions, wherever it was drawn through out the three worlds.
 

To please Agni, the fire-god, Krsna arranged to offer him the Khanava forest. The Lord, asked Arjuna to burn down the forest and would accompany him as his charioteer. Agni (the demigod in charge of the southeastern portion of the universe) was so satisfied with the offering that he presented Arjuna with the Gandiva bow, a team of horses, a chariot, two inexhaustible quivers, and armor.
 

The Lord’s chariot, yoked with the horses named Saibya, Sugriva, Meghapuspa and Balahaka. Srila Viswanätha Cakravarti quotes the following text of the Padma Purana describing Lord Krsna’s chariot horses: Saibya was green like a parrot's wings, Sugriva yellow-gold, Meghapuspa the color of a cloud, and Balahaka whitish.”  SB 10.53.6
 
 

On the battlefield (where Sri Krsna attended Arjuna out of friendship), the flowing hair of Lord Krsna turned ashen due to the dust raised by the hoofs of the horses. And because of His labor, beads of sweat wetted His face. All these decorations, intensified by the " so called wounds " dealt by my sharp arrows, were enjoyed by Him. Let my mind thus go unto Sri Krsna.  This sloka was recited by Grandfather Bhisma dev as he lay on the bed of arrows.