There are examples in Scripture of presbyteries existing and functioning. Acts 15 is an example of a presbytery functioning. Paul says that Timothy was ordained by a presbytery (1 Timothy 4:14).
In Acts 15 we see a meeting of a general assembly of the apostles and the elders of all of the churches at the time. It was not restricted, say, to the Presbyterian of the Jordan River.
Timothy had hands laid on him by the elders of a church, not elders of churches in a particular geographic region. Here is the passage from I Timothy 4.
12 Let no one look down on your youthfulness, but
rather in speech, conduct, love, faith
and purity, show yourself an example of those who believe. 13 Until I come, give attention to the
public reading
of Scripture, to exhortation and teaching. 14 Do not neglect the spiritual gift within you, which was bestowed on you through prophetic utterance with the laying on of hands by the presbytery.
First, we see that Timothy was a young man (therefore, by definition, not an elder). We also see that he received a spiritual gift through prophetic utterance with the laying on of hands by the presbytery. Is this modern Presbyterian ordination? I think not.
Thus, the principle of geographic divisions of the church remains just that - a principle without direct support from scripture.