is charging is not moving but at less than 2MU from
.........
At the turn of (chariots) could the on the left move to the right to offer 8 dices of chariots against 4 dices of cavalry or does the restricted area applies ?
Restricted zone applies "for normal movement only". (Top of p74.)
But note that the left hand chariot cannot move to the right hand end after the impact phase - the non-active player can only expand to match where the enemy has an overlap. (p72, last bullet.)
So that expansion will have to wait until the next turn.