The maximum duration of the era in the realms speed x2 is 8 months, 4 months for realms speed x4, but the era may end before expected, approximately 20 weeks after the beginning of the era (speed x2) or 10 weeks (speed x4) the competition "Lords of the realm" starts and the realm ends if one alliance manages to maintain at least 60% influence range for minimum 84 hours (for realms speed x2) or 42 hours (speed x4). It mostly depends of the time of last restart of the realms, their speed and developements in the competition Lords of the realm. The realm International 160, speed x4 will be restarted soon, the stage for winning the realm via Lords of the realm competition will be activated in this realm on February 17 at 4 pm server time (GMT + 2).
For now, there are two international realms with speed x2, realm 161, the new era has started a month ago, and realm 175 has started on October 29, the competition Lords of the realm will approximately begin about 4 to 5 weeks from now, registration can be made via
http://www101.imperiaonline.org/imperia/game_v5/game/register.php?realm=175&ipid=772004&c=22809febfc838a295c1c9f846cb96605There will be more x2 international realms later, but for now I don't have information about the dates of their opening, it wlll be officially announced in the game.