Sometimes we can choose not to include a subject pronoun in a sentence because:

A pronoun is used to substitute a noun. In order for it to substitute, it must have a clear antecedent. Personal pronouns are used to substitute nouns with ownership. There are three persons point of view.1st person is when the subject is the one who is speaking (e.g. I, me, my, mine, we, us, our, ours). 2nd person is when the subject is the one being spoken to (you, your, yours). 3rd person is when the subject is the one spoken about (he, him, his, she, her, hers, it, its, they, their, theirs).

They were buried in indian burial bounds.status of them can be found in indian burial mounds.hope this !