'Very numerous were the inhabitants of Ireland at this time [the time of the sons of Aed Slane in the seventh century], and their number was so great that they only received in the partition 3 _lots of_ 9 _ridges_ [immaire] _of land_, namely 9 ridges of bog land, 9 of forest, and 9 of arable land.' «The _run-rig_ or _Rundale_ system in Ireland and Scotland.» Taking those two passages together, and noting that the word for 'ridges' (_immaire_) is the same word (_imire_, or _iomair_[299]) now used in Gaelic for a ridge of land, and that the recently remaining system of strips and balks in Ireland and Scotland is still known as the 'run-rig' system, it becomes clear that whatever there was of arable land in any particular year lay in open fields divided into ridges or strips. There are, further, some passages in the _Brehon Laws_ which show that at least among the lower grades of tribesmen there was joint-ploughing. And this arose not simply from 'joint-tenancy' of undivided land by co-heirs,[300] but from the fact that the tribesmen of lower rank only possessed _portions_ of the requisites of a plough,[301] just as was the case with Welsh tribesmen and the Saxon holders of yard-lands. There can be little doubt, therefore, that we must picture the households of tribesmen occupying the four 'tates' in each 'quarter' as often combining to produce the plough team, and as engaged to some extent in joint-ploughing. [p227] At first, what little agriculture was needful would be, like the Welsh 'coaration of the waste,' the joint-ploughing of grass land, which after the year's crop, or perhaps three or four years' crop, would go back into grass.[302] But it would seem from the passage quoted above, that the whole quarter of normally 120 Irish acres was at first divided into 'ridges'--possibly Irish acres--to facilitate the allotment among the households not only of that portion which was arable for the year, but also of the shares in the bog and the forest. No doubt originally there was plenty of mountain pasture besides the thirty, or sometimes sixty scattered acres or ridges allotted in [p228] 'run-rig' to each 'tate' or household. In the seventh century, as we have seen, the complaint was made that the pressure of population had reduced the shares to twenty-seven ridges instead of thirty.