I started playing contact rugby at 10 years old but I think 8 or 9 years old is a good age. The reason I don`t think contact should be played before that is because rugby is quite a complex sport and the rules take a while to learn. Children younger than 8 or 9 could get overwhelmed with all these rules and the game wouldn’t be as fun. Rugby is also not for everyone I think parents are the best judges for this type of thing because children are different. Hope this post is helpful I will be talking about more things related to this topic in future posts.