Given how often solar eclipse are used to date historical events, I think an international calendar should begin on the day of the first recorded total solar eclipse.
If scientist are right about some Irish petroglyphs, it is currently the year 5365. Christ was born in 3340. The Egyptian middle kingdom period lasted from 1300 to 1558. The Ottoman empire took Constantinople in 4793. Star Wars episode IV was released in 5312.
Proto-writing systems emerged sometime between -40 and 240. The Olmecs emerged in roughly 2140. The Aztec Empire was founded in 4768. The Zhang dynasty began in roughly 1574.

















