I use to watch it as a child. It was about a brother and sister, they were young, living in a house near a pond. One day Indians came and took the sister. When the brother was older he went to search for his sister. He ends up finding her with the Indians and she had married an Indian and I believe had a child of her own. Before he found out she was there I think they had him do these difficult games in order to save his life, I can't remember exactly.

Sounds like Against a Crooked Sky (http://www.imdb.com/title/tt0072615/)