Season 1 of Kingdom covers chapter 1 to 173 (though some mini-stories are left out or some changes are made to them. Additionally, the Assassination Plot Arc was not animated even in season two and Escape from Zhao Arc was moved to season two). It began airing on 2012-06-04 and has finished it's run with a total of 38 episodes.
The season is by Pierrot.
A young boy named Shin along with his friend, Hyou are servents. They dream of a better future as they aim to become the greatest generals underneath the heavens. Realizing this dream will be difficult to achieve, they start training with wooden swords. They have over 1000 serious bouts against each other and train for a wide variety of situations. One Day his friend's dreams are one step closer to achieving it. Through circumstances, Shin becomes involved and on a fated day he meets a person that can help him achieve his dream, although this person needs his help as well. Due to this Shin becomes a target by some powerful people and Shin has to fight to survive. Trough his journey he makes some unexpected friends and starts learning about the nature of war and the nature of politics. If Shin wants to achieve his dream, he will need to climb up in rank and gain achievements, rampage on the battlefield and gaining knowledge and military might.