If twenty men among you are steadfast, they will overcome two hundred.
— The Qur'an (8:65)
The answer to European polearms, the Tabardiyyah Infantry are very similar to Russian Berdishy Dvor, with several exceptions, however: while they also have the Berdishy Dvor’s food-saving ability, they have a ramp cost of 4 wealth per unit as opposed to 8 metal. While this isn't such a bad thing especially since your units won't be consuming so much metal, what makes the Tabardiyyah an issue is that only factions that have researched both Five Pillars and Monarchy can have them and can only be recruited from a Nobles' Court. This means that there are substantial overhead costs that you will need to pay before you can recruit these heavy axemen to be the vanguard of your minions.
Nevertheless, the Tabardiyyah can constitute a powerful corps of heavy assault infantry, meant to both disrupt spear formations and gaffe cavalrymen off their mounts — only as long as you keep them away from javelins and arrows. Tabardiyyah Infantry are especially useful for the Saracens who have fast-running but weakly armoured spearmen, so they now have a useful melee unit which can be used to impose the will of sultans on the battle line.
- Early Supremacy — As billmen can be obtained in the pre-Centralisation late game, they are a great boost for those capable of recruiting them, although they will soon be outranged by the costlier but more efficient Pikemen.
- Planning for Obsolescence — Once Centralisation is achieved, Billmen become weaker as a defensive force. This means you should use offensive tactics accompanied by cavalry — cut your enemy down before he can stab you!
The elite warrior class of the Arabophone nations existing north of Mecca in the Intermediate Mediaeval Era were not always native Arabs, but were in fact Arabicised Turkish "slaves" (hence their name, "mamluk", lit "those who are owned"). A foreigner, isolated from the blood feuds and scheming that dominated politics in early modern Islamic society, made a better choice compared with natives for the Sultan's own attendants, as his own safety depended on his loyalty to his master, but such power came with a price: the mamluks would eventually form clans that carved out fiefdoms for themselves throughout the Caliph's lands and beyond, forming what are now known as the "mamluk" dynasties. Of these, the most famous clan would be the Mamluk sultanate, which dominated Egypt and the Red Sea for well over two centuries, before being subsumed into the Ottoman Empire in 1517, as well as the Bahrids who were responsible for forcing out western rule from the Levant in the 14th century, ensuring the Islamic domination of the Middle East for at least 4 centuries.