Ireland's previous lowest position was eighth on a handful of occasions, but it could have been worse than ninth had Scotland not slipped to a 23-16 loss to France at the Stade de France in the final RBS 6 Nations match of 2013.
The other five nations all ended the Championship's final weekend in the place they began it, although in the cases of Wales and Italy significantly closer to the sides above them in England and Tonga.
Wales destroyed England's hopes of a first Grand Slam since 2003 with a dominant 30-3 victory at the Millennium Stadium to retain the title and slash the deficit between the two to just 0.36 rating points.
The heavy loss for England not only puts their mantle as the leading northern Hemisphere nation under threat, but also means their deficit to Australia in third has now grown to more than three rating points.
Italy's margin of victory over Ireland was not big enough to improve their position of 12th, although they have closed to within four hundredths of Tonga above them, as well as only eight tenths behind Scotland in 10th.
IRB WORLD RANKINGS (as of Monday, March 18):
Last week's positions in brackets -
1(1) New Zealand 90.08 rating points
2(2) South Africa 86.94
3(3) Australia 86.87
4(4) England 83.72
5(5) Wales 83.36
6(6) France 81.59
7(8) Samoa 78.71
8(9) Argentina 78.71
9(7) IRELAND 78.05
10(10) Scotland 76.86
11(11) Tonga 76.10
12(12) Italy 76.06