Mughale-e-Ajam / Gadar are Biggest movie in this genre which comes first in mind. Lagaan had got huge appreciation and decent BO success.
I think only ATBB movies in this genre are Mughal-e-Aajam and Gadar (Correct me if I'm wrong).
Recent successful period movies are Bajirao Mastani, Jodha Akbar, Devdas, but there are also quite a lot of flop/unsuccessful movies e.g. Tubelight, MohejoDaro, Raabta, Veer, Asoka, 1947 Earth, Mangal Pandey, which stars big superstars and directos.
Looks like there is big possibility to go wrong in this genre even from very good directors.
Will SLB and Victor join list of successful period film's director with Padmavat and ToH ?