Pretty much the same as clothing looked in 15th century Morocco.

As an example compare this 15th century portrait of Abu `Abdallah Muhammad XII, the last moorish ruler of Granada, with the Dark Knight in the Knights panel of the S. Vicente hexaptych from the same time: the Dark Knight supposedly represents Portuguese prince Fernando, the saint, who offered himself as a hostage in exchange for his brother Henrique after the latter lost the battle of Tangier, and who ended up dying in Fez. The knight is accepted as prince Fernando, because he's dressed like a moroccan knight (that and the fact that the disgraced purple knight is an actual live portrait of prince Henrique).

Also worth noting the simplicity of both Muhammad's and Fernando's garments, compared to the lavish garments of Fernando's brothers in the same panel (Red Knight - Prince João, Green Knight - Prince Pedro and Purple Knight - Prince Henrique), all proper Portuguese Catholic Knights.