To expand on Tamerlane’s history of Scotland:
The formation of Scotland was a complex affair. Basically for centuries there were four different groups competing among themselves in the area:The Picts, the Scots (i.e. the Dalriadans/Godolic Celts), the British (i.e. the Brythonic Celts) and the Anglo-Saxons (i.e. Germanic tribes), adding to these four groups, late in the day arrived the Vikings (i.e. Norsemen).
The British and Anglo Saxon groups were by no means in any way united among themselves and if two kingdoms belonged to the same group it made very little differnce to whther or not they went to war . The principle British kingdoms in the area were Strathclyde, Gododdin and Rheged and the pinciple Anglo-Saxon Kingdoms were Bernicia and Northrumbia. Rheged (which fractured into a Northern and Southern kingdom)and Northumbria had their main territorial bases in what later became Northern England, but at various times had territory in what became Scotland (this is especially true of the Northumbrians). These two groupings dominated the lowlands of what became Scotland (which includes modern Scotland’s capital Edinburgh which then known as Dunedin and was the captial of Gododdin before falling to Northumbria) fighting among themselves for control of this area. The Kingdoms of Rheged and Gododdin eventualy fell, mainly due to the efforts of the Anglo-Saxon kingdoms leaving the ‘borders’ a Germanic stronghold and cleaving the remaining British Caledonian territory into two. Strathclyde (whose territory was mainly based in what became Scotland and whichincluded the city founded by St. Mungo which went onto to become Scotlands most populace city: Glasgow)was genreally speaking the strongest of the British kingdoms in what became Scotland still fully independent until several decades after Kenneth MacAplin founded the Kingdom of Scotland and not fully subsumed into the kingdom until 1018.
The Picts and the Scots dominated the geographically larger highlands, again not necessarily united among their groupings with Pictland at various times being split into North and South kingdoms and various sub-kingdoms and Dalriada at times divided into warring septs. The Scots settled in Great Britian in the same manner that the Anglo-Saxons and later the Vikings, initially as raiders, before settling down and consolidating territory. The kingdom of Dalriada started life ironically in Ulster, then strecthing across the Irish sea and taking in mid-west Scotland and the neraby Irelands, before it lost it’s orginal territoral base in Ireland. Militarily throughout this period of competing kingdoms the Picts dominated (as well as dominating the Scots, they later managed to dominate Strathclyde and halted the adavance of the Anglo-Saxons) managing to completely overrun Dalriada twice reducing it to their overlordship. However Scots culture managed to do what Dalriada could not and despite the fact that at the time it was the Picts who ruled the Scots, completely supplanted Pictish culture. This was primarily due to evangelisation of the Picts which was carried out by among others Irish monks, also playing a role was undoubted Irish immigration into western Pictland (Atholl). Kenneth MacAplin (who was actually not the first Scot to rule the Picts, all of them gaining control partly via the same method of strategic marriage), in the ninth century frimly united the two kingdoms into a single kingdom in the ninth century.
In the century preceding the founding of the Kingdom of Scotland, a new foce appeared on the scene - the Vikings. They did not have a significant role to play at this stage (though later, IIRC, interstingly the first King of England to get the King of Scotland to pay homage to him was none other than the Viking Cnut the Great (most famous for veinly commanding the tide to go out to illustrate the temporal limits of kingly power), but what they did do was to take control of the outer isles.
Finally, set up, getting onto the OP: St. Patrick may well of been born in Scotland before being taken as a slave by Irish raiders, also another connection is that St. Patrick was in correspondance with the King of Strathclyde. Apart from that I cannot think of many other connections with Scotland (though I imagine that the descendants of the large numbers of Irish people who moved to Scotlands’s largets city Galsgow during the potato famine may celebrate St. Patrick’s day). Though one thing, why would St. Patrick in particular be held in high regard by anyone opposed to tyrannical oppression?