Summary of Historical Hnefatafl.

Sámi Tablut 9x9.

By November 2011, we had identified the Sámi Tablut rules:
Summary of Sámi Tablut.
The Sámi Tablut setup and rules are given directly in Carl von Linné's 1732 diary.

Welsh Tawlbwrdd 1x11.

The Welsh Tawlbwrdd is described in the 1587 manuscript of Robert ap Ifan.
We found a best bid on the rules based on the Sámi Tablut (December 2012):
Summary on the Welsh Tawlbwrdd.

Brandubh 7x7.

After briefly testing various possibilities, the Saami rules were found to work best also for Brandubh (March 2015):
Summary of Brandubh.

All three variants appear to be the same game: the historical Iron Age Hnefatafl, only played on various board sizes.

Measured game balances:
Tablut: 117 attacker wins per 100 defender wins.
Tawlbwrdd: 115 attacker wins per 100 defender wins.
Brandubh2: 136 defender wins per 100 attacker wins.

See the Historical Hnefatafl rules here.