Plus two range damage is also in for Vortex by now. So, the damage from these Yeoman starts to get severely out of control, even on top of those javelins with their bonus ranged armor.

Dark age pressure on pitmine is a classic strategy for Lancaster, super effective dark age civ courtesy of the extra food on sheep, and Malians are always a prime target for that.

Yeomen do enough damage against the sofa in the feudal age without the imported armor.

By applying early pressure, House of Lancaster can prevent Malians from starting their cowboom, which is critical because Malians rely on cattle for a powerful economy.

Against the Malian Donso + Javelin composition, House of Lancaster's answer is to go for heavier units like Demilancers or upgraded infantry by advancing to Castle Age and getting relevant upgrades.