For many years the letter to the Ephesians has been regarded as a general epistle or letter, addressed to wide variety of churches and therefore containing very general instruction with no specific historical context or church issue in mind. This general nature was believed to have set Ephesians apart from the other New Testament letters for which it is plain that some or other issue in the church caused or facilitated the letter being written. For example, in Corinth there was sexual immorality in the church, lawsuits amongst believers, and a wrong understanding of what it meant to be spiritual that caused Paul to write 1 Corinthians. In Galatia it was the Judaizers promoting a false gospel of faith and circumcision, and so on.
Ephesians seemed to have no such particular issue, save perhaps the general challenge of Jewish and Gentile relations in Ephesians chapter 2.