Of curse countries in our Medieval times had borders. They were fing kingdoms. Countries had borders since first countries were invented.
They may not have been as precisely defined and marked as modern ones but they sure existed and people sure did get pissed off about them and other dirty foreigners getting into places where they dont belong.
Thats not the problem here. The problem is that the reason why there is animosity towards refugee Tieflings - by Druids is never explained in a way that would make any sense in this setting and its lore. Especially in the situation where a third force is attacking everyone. This is not a case of Earth borders and politics and problems, modern ones or historic ones.
The whole sub plot is based only on vapid extremely superficial generalizations without any background or any specifics, and the same kind of blunt cheap generalizations are used in the trial. The player is never allowed to argue or ask or point out the most obvious issues about the whole deal.
Khaga idea is this: Once the refugees are gone, whichever way - she can cast the big ritual and seal the Grove, mkay?
Well... okay, bu that immediately raises several really obvious questions.
1. If the ritual will protect the grove... why doesnt she just do it and protect everyone?
2. If the refugees are creating any issue why that could not work...like maybe there isnt enough food for everyone, why are we never told anything about it and we cant even ask about it.
3. Obviously - a druid grove should not suffer from any food problems even with refugees around.
4. Why does anyone think that attacks are happening only because of refugees? Is that based on any info at all? Where the F did they get that idea?
5. Wouldn't Druids be extremely miffed about bands of Goblins killing everything and burning and destroying everything they can around them?
6. If Khaga is a Shadow Druid and if that isnt just used to show "she is evil" - then she should consider everyone enemies. Especially the Goblins.
7. If the Grove is sealed from the outside - doesnt that mean all the Druids would be trapped inside and unable to do anything about a Goblin army ravaging the whole area?
8. Do they want to stay sealed inside the Grove... forever?
9. Wouldnt they want to know more about this army thats attacking everyone?
... And on and on and on , these kinds of questions never stop because the whole situation setup is done so badly it cannot exist unless all these considerations are simply removed and not allowed to be considered.
And the trial is even worse. The player never even gets a chance to ask about any of these most basic and obvious considerations.
So i played in the Forgotten realms since the second edition i can explain some things:
1) Usually when such ritual is done is to protect the specific druidic circle. Druidic circles often are zone in the wilderness where there is a Mystical force usually dependant on a natural artifact or simply tied of one of the nature Gods ((in this case the Artifact of Silvanus) normally any druidic circle will forbhid the access even close to a zone like that if not for very specific and lack of choices cases. And the artifact was stolen that was a great offence enough for any druid figures a Shadow Druid like Khaga they are very extremist.
2)For the druid the concept of food and suvivability is tied also with local natural resources. THe refugees are many and they require a lot of food. They would hunt around for wild animals to feed theyrself if allowed to stay permanently they will cut trees and plant crops ruining the natural fauna and flora and the echosystem of the place that is in part already proved considering we have a village not much distant from it.
3)Wrong. Druids use divine powers to create food even with that sort of spell is not something they can abuse that would bring down the balance they strive for. Nor they can allow the refugees to deplete the natural resources around.
4)It is a common staple of the druidic circles. A stranger is a potential trouble. Many stranger is a potential threat. Not to mention those strangers were seeking shelter from the druid. The old Archdruid accepted this because he represent the more tollerant druid part. However more numbers more attention. More attention more dangers for theyr sacre circle.
5)Goblin are not considered inherently a threat by Druid per se. Unless those goblins are attacking them directly however Goblin are often seen by druid as part of nature as well as they have a tribal society and not a civilized one. Goblins don't make crops nor build cities they just live in the wilderness and are opportunistic in nature. A goblin pack would hardly attack a druidic circle is more like to prey on paesants or adventurers attacking in numbers.
6)Again for shadow druids and also for normal Druid goblins are seen like creature that despite of everything live with nature as they have primitive tribal society. They would accept more gladly a tribe of Goblin nearby than a pack of people that want to get settled also the goblin of this story are not acting natural they are driven forward and bold by this faith of the absolute. Goblins usually prey in easy targets.
7)Is a ritual of isolation quite common in to Druidic traditions. Is a Ritual that isolate the circle that protects the relic and preserve the heart of the druidic circle. Usually Druids rely in this ritual to shield theyr Circle from danger. They can just do that allow the situation to unfold with the time and then resume the ritual to open the circle again.
8)Not forever. But theyr priority is preserve the druidic Circle probably they will be sealed inside till will be more safe for them to break the seal.
9)On normal circumstance they could. However since a Shadow Druid was chosen as the second Archdruid while the other was away that priority changed. The old Archdruid actually was out seeking answers he also examinated the tadpole and got attacked by a drow that was infected by it. This also answer why they are so on edge at what is happening round. They have the refugees then they had a Nautiloid crashing nearby the groove. On top of that the old Archdruid was attacked by a drow infected with a tadpole. This combination of circumstances is already aggravating a situation that was hard to start with.