Adapted from the light novels by Yoshiki Tanaka (田中 芳樹) and illustrated by the mangaka of Fullmetal Alchemist, Hiromu Arakawa (荒川 弘) , it is a manga with great artwork.
Plot: A young prince of the Kingdom of Pars, Arslan went on his maiden battle. The Parsians suffered a crushing defeat agains the Lusitanians thanks to the betrayal of a Marzban (general) and the arrogance of their king, Andragoras |||.(I really hate that guy ) The city, Ecbatana was lost and Arslan must recover it with the help of his new comrades.
It is still on-going so... If you really want to know the story that bad, you can read the LN. I have only found one or 2 volumes is English but I have found about 13 in chinese. I had hoped to know the full story but the light novels are still on-going too :'(