You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Umayyad_Caliphate

Context:
The books written later in the Abbasid period in Iran are more anti Umayyad. Iran was Sunni at the time. There was much anti Arab feeling in Iran after the fall of the Persian empire. This anti Arab feeling also influenced the books on Islamic history. Al-Tabri was also written in Iran during that period. Al-Tabri was a huge collection including all the text that he could find, from all the sources. It was a collection preserving everything for future generations to codify and for future generations to judge if it was true or false.

Question:
In the later Abbasid era, what branch of Islam did Iran adhere to?

Sunni