I've discovered during my world-building that there is a slight issue between the races of Man and Centaurs. In my world, the two races are allied with each other after banding together during the Greenskin Invasion where the Centaurs proved themselves to be excellent skirmishers and heavy calvary. After the war, the human king rewarded the nomadic people with a place to call their home and the eternal friendship of the empire. With some help from the Dwarves of the Forged Mountains and the Gnomes present within the empire, they managed to build a large city for the Centaurs to call home. The city is much larger than normal cities as it's more spread out and buildings take up more space and where stairs are needed, they are replaced with ramps and large elevators operated by pulleys and weights. Now the problem lies in that Centaurs are half man and half horse. The empire is well known for its Gryphon Knights. Knights that ride upon Gryphons which are half eagle and half lion. Gryphons favorite prey are horses. They descend from the skies and attack the horses by ripping its neck out and swarming upon them. Though the beasts are well tamed, wild Gryphons have been known to stalk the lands of the Centaur people and even some of the trained ones have been reported to attack Centaurs if their owner has not fed them in the morning. 

It's things like these that make me giddy and excited for when I'm finally able to put it all on the table and have my players learn and experience these things for themselves as I am by simply reading through paragraphs of these beasts from not just the current material, but even previous editions as well as discussion threads on Reddit and other places online.