Pioneers are used to expand your Kingdom. Training one allows you to build a City on fertile ground or an Outpost on the fringe of civilization. Where you choose to place a city is very important. The potential of a city is based on the yields of tile you settle on. You can see the yields of a particular tile by hovering over the settle button or clicking the tile yield icon on the terrain window. There are three kinds of yields: Grain, Materials, and Essence. The higher the Grain yields the more food your city will produce for itself, and thus the city will have a higher possible maximum population. The higher the Material yields the more production your city will be able to produce, and thus the city will train units and construct improvements faster. At least one Grain is required to found a new city on a tile. The Essence yield indicates how many enchantments can be cast upon that city. In addition to being able found cities, your pioneers can also build outposts. Outposts will provide you with vision of a specific area and spread your influence without being a whole new city. Additionally, you can send pioneers to outposts to upgrade their attack and defensive capabilities. Choose wisely, as all these action will consume your Pioneer unit.