Scottish and Irish Gaelic have been parting company since the 12th century. That, at any rate, is as far back as our oldest evidence, the Book of Deer (from Aberdeenshire) allows us to date this most amicable of separations. Curiously it was around that time that the scholars and poets of Ireland got together to do some planning. Out of the Gaelic dialects of Ireland they devised a code of grammar and rhetoric that would serve them well for half a millennium. But it took no account of Scotland.

In fact, as a recent study by Wilson McLeod shows, the Gael of Scotland were seen by the native Irish not so much as pioneers in a new land ripe for colonisation, as exiles who should return to aid them in their hours of need.

Despite almost ritualised titles like ArdOllamh Eireann agus Alban - Chief Poet of Ireland and Scotland - there was in reality an imbalance. To the Irish the Scottish Gael belonged to a quaint otherworld symbolised neatly by mythology.

When the young Cu Chulainn needed the best martial arts training the world could offer, he sought out the amazon Sgthach in Skye to give it to him. When Naoise and Deirdre fled the wrath of king Conchubhair of Ulster they found solace hunting and picking berries on the shores of Loch Etive.

In Scotland's own mythology, by contrast, Ireland was the land of sophistication. No Highland chief or learned man was worth a spit without Irish blood in his veins. Such people went to Ireland on business, be their business war, trade or scholarship; if an Irishman came here it was, well, a oncein-a-lifetime adventure holiday. But at least there was a relationship. After the traumatic events of the 1600s - most of the Highlands turning to Protestantism, while the Ulster Plantations "took the core out of the Gaelic apple", as Professor William Gillies has so aptly expressed it - Gaelic Ireland and Scotland went their separate ways.

There were big differences. The power of the Irish chiefs was broken at Kinsale in 1601; that didn't happen in Scotland till Culloden in 1746.

Scotland had its Clearances, Ireland its Famine. In Scotland the Gaelic language preserved a vibrant music, literature and folklore, but its speakers probably never numbered over a million; in Ireland a major European language was simply thrown away by four million people facing starvation or Ellis Island.

In the 20th century, too, there has been a failure to connect. Irish became the first official language of the Free State and the Republic, a badge of militant nationalism in the North; Gaelic in Scotland has been the toy of the resolutely apolitical An Comunn Gaidhealach and its "Royal National Mod". The result? Curiously, while Irish censuses consistently show the language being spoken by a million people, the real figure is now something like 65,000 - precisely the number of Gaelic-speakers recorded by the Scottish census of 1991. After taking different routes, we have arrived at the same place.

AS the millennium ends, then, Irish and Scottish Gaelic are finding common ground. The languages are mutually comprehensible (just), which makes it difficult to be fluent in both; but there are probably more people who can claim to speak both than ever before, and there's even an organisation (Tuigsinn, "Understanding", based in Belfast) to help them.

There are courses in Irish for speakers of Scottish Gaelic, and vice versa. Iomairt Chaluim Chille, the St Columba Initiative, born of a visit to Iona by former Irish President Mary Robinson, links the Gaelic of Scotland, Northern Ireland and the Republic through three full-time officers and funding for projects. Academically, Edinburgh University's Department of Celtic has a Centre for Irish Studies, and Scotland's departments of Celtic have always recognised the importance of Irish as the linguistic root and literary bedrock of our own Gaelic. This has often been reflected in staffing. The current occupant of the chair of Celtic in Glasgow University, Cathair O Dochartaigh, is an Irishman, and our other two departments of Celtic (in Edinburgh and Aberdeen) also have Irishmen on their staff.

In fact, while Gaelic Scotland outside academia enjoys rediscovering the Irish, the universities have if anything the opposite problem - while the Irish education system produces a surfeit of young academics qualified to teach Irish and even Scottish Gaelic, centuries of persecution and neglect by the Scottish education system have resulted in a worrying dearth of academically-qualified Gaelic-speakers. Finally there are literary links. Of 100 poets in An Tuil: Anthology of 20th Century Scottish Gaelic Verse, two (Victor Price and Rody Gorman) are Irish. Conversely, by the 1970s Sorley MacLean was being recognised in Ireland, where he had a cult following, as the greatest Gaelic poet of his day.

This led to an annual exchange of poets and musicians between the two countries and a trilingual anthology, Sruth na Maoile. That is the name that has come to symbolise the new Gaelic dynamic.

"The North Channel" is a bit of a misnomer, but Sruth na Maoile, "The Current of the Mull" (of Kintyre, that is), is the panGaelic name for that fast-flowing stretch of water that divides - or connects? - Gaelic Scotland and Ireland.