There has traditionally been great antipathy between most clansmen and the more aggressive species of monsters and non humans. Over the centuries there have been several wars fought between the humans and some species indiginous to Caledonia, most recent have included the Formorians and the goblin kingdoms. At times, a treaty has resulted in periods of relative peace, but these have never lasted long.
The non intelligent species are treated as any other harmful animal would be, if one endangers a community, then it is destroyed. If the numbers reach dangerous levels, their lairs are located and the creatures wiped out. Over time, many of these creatures have become concentrated in remoter regions, and some have dwindled in number.
In a similar fashion, continuous warfare with the more intelligent tribal species that prey on the clans for food or resources has resulted in a zoning of such monsters around the more populated areas. They have retreated to inhospitable areas of Caledonia, or those places that provide good defence and cover, such as mountains and forests. The Highland clans still clash regularly with these species, but most hill and lowland clans have borders, with a no man's land separating the two protagonists from continuous conflict. Indeed, some areas of the country are lucky to even see some of these creatures from one year to the next.
Certain species have, as individuals or as a tribe, made peace with the clans, and some have even been accepted as fellow citizens. Whilst this is not common to all areas of Caledonia, the lowland regions, with their more worldly attitudes, have even welcomed inter marriage with some of them. Many of these individuals have gained rank and privilages from the ruling authorities, and are classed as "heroes of Caledonia". Like the human clansmen who have also gained great renown, these creatures travel the transport circles and attend the great gatherings of nations. They are as likely to be called upon in times of battle or political intrigue as their human counterparts.
This freedom to travel, command clansmen, and lead warbands can sometimes cause problems with local clans. Particularly in remoter areas where any non human is a potential threat. Indeed some of the highland, island and moorland clans would not even be aware that such creatures were their allies, and have been known to attack and even kill such heroes without ever knowing the truth. Political issues with non humans is also a factor in potential conflicts. There are many clans who have spent their lives fighting certain species, and to have one of them giving orders to them is the last thing they want.
The same can be true for creatures coming into Caledonia from other countries or planes of existence, particularly those connected with demon realms. Centuries of tradition cannot be swept away in a single lifetime, and tolerance can be in short supply if personal experience has caused a hatred or fear of such races in the past. Undead are also recieved with varying degrees of emotion from individual clans. Whilst some have many examples of the useful nature of the mindless unliving, performing dangerous tasks in the mines, armies and labour gangs, others will attack them on sight. Intelligent undead are even less welcome and face greater levels of threat from the non-cosmopolitan celts living away from the towns.
In general, the more remote the clan, the more likely it is to be at odds
with a non human species, particularly if it is competing for the same resources.
In a country where the land itself can kill an unwary soul, is it any wonder
that there is antipathy towards those different from themselves, the greater
the difference, the greater the threat perceived.