Islands of automation was a popular term used largely during the 1980s to describe how rapidly developing automation systems were at first unable to communicate easily with each other.
[1] Industrial communication protocols, network technologies, and system integration helped to improve this situation.
Just a few of the many examples of helping technologies are Modbus, Fieldbus, Ethernet, etc.
It is more recently used by automation specialists to describe a discrete and fully enclosed automated system applied in a largely manual environment.
In today's interconnected world it is uncommon for automated systems to be fully stand alone.