[tom the eldest]

The easterling do have some military advance.for example,the have an effective anti-cavalry techniques,which is why they were feared by rohirrim and gondor.they also had some advance in agricultural,seeing that most of sauron food were made in rhun,due to the ashes of mount doom make fertile land in rhun.they armour is also pretty different from the west.the west had wing-shaped helmet and iron armour,while the easterling had fearsome dragon-shaped helmet and golden armour.considering that the easterling can make gold into a strong armour,i think that they had some advanced metalurgy techniques.