AI overview
I don't have enough context to write an accurate overview of "638." The context provided only indicates it's a year, but without additional information about what specifically happened in 638, what historical period or event it refers to, or why it matters, I cannot write a factually accurate explanation.
AI-generated from the Wikipedia summary — may contain errors.
Article
The Muslim invasion of Anatolia and Armenia
Year 638 (DCXXXVIII) was a common year starting on Thursday of the Julian calendar. The denomination 638 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.