To quote from that paper on Ulster-Scots Music by ‘Queens University's – School of Anthropological Studies’: 
“Up until the end of the eighteenth century, itinerant harpers regularly crossed back and forwards between Ulster and Scotland, playing for the Gaelic and Anglo-Irish aristocracy, as well as prosperous Ulster-Scots families. The Harping tradition declined as European classical music came to occupy the attention of the ruling classes, but before they disappeared from the scene, harpers interacted with fiddlers and pipers in Ulster, and some of the features of the Gaelic song tradition were preserved, particularly in the emerging genre of Orange songs”
“In Scotland, in the area once inhabited by people known as Picts, musical instruments that are obviously frame harps are represented on six monuments. Perhaps earliest is the example carved on a monument known as Aberlemno No. 3, a red sandstone slab over nine feet in height, standing beside the narrow road leading from the town of Forfar to the village of Aberlemno (Angus).” 
This being the case the Harp has a far longer history in the hearts of the Scottish people than the Bagpipes, as shown by these quotes below & the information on this web page: 
“Many outsiders associate Scottish folk music almost entirely with bagpipes, which has indeed long played an important part of Scottish music. It is, however, not unique or indigenous to Scotland, having been imported"
& this
"The harp, or clarsach, has a long history in Scotland, rivalling even the bagpipes for the position as national instrument.
Triangular harps were known as far back as the 10th century, when they appear on Pictish carvings, and harp compositions may have even formed the basis for pibroch, the folk bagpipe tradition."
It is known that the Pipes had only one drone until the mid 1500’s when the second drone was added.
The first written mention of the ‘Great Pipes’ was in 1623 when a Piper from Perth was prosecuted for playing on the sabbath.
The third drone only appeared early in the 1700’s.
So compared to the Harp, the Great Highland Bagpipe is just a youngster!