As the old Samaria no longer existed in that time, the question arises: does the Samaria in the book of Acts refer to the region? The naming of Samaria can point to the new city Sebaste, but in the New Testament it is often referring to the province of Samaria. Here the name Samaria probably refers to the province, including the capital. Acts 8:25 “many villages of the Samaritans” seems to underscore this notion. In Acts 8:5, it says in old manuscripts the city of the Samaritans.
In Acts 8:8 it also says the city.
That could have been Shechem (as religious capital) or perhaps still Sebaste.
5 Philip went down to the city of Samaria and proclaimed to them the Christ.