Howling:Great Intelligence history and origin

A lot of us are very muddled and confused over the implication in Series 7 that the Great Intelligence began in the late 19th century as a manifestation in the psychic snow of Walter Simeon's dark thoughts, which survived beyond his death and grew and expanded over time; due to continuity errors such as the Yog-Sothoth backstory from the New Virgin Media books, and Padmasambhava's advanced age suggesting the Intelligence possessed him circa the 17th - 18th century. While mostly speculation, I do have a theory or two explaining it to share, both assuming the New Virgin Media books non-canon:

TroopDude ☎  20:11, May 21, 2013 (UTC)
 * 1) After its creation from Simeon's dark thoughts and the psychic snow in the 19th century, the Great Intelligence at some point travelled back in time to the 17th or 18th century or earlier, and from there began its plans with Padmasambhava and the robot Yeti in Tibet.
 * 2) At least one or more of the temporal copies of the Great Intelligence that were scattered across the Doctor's timeline after the Intelligence entered it on Trenzalore survived after these echoes of the GI were stopped by the ones of Clara Oswald, and at least one of these surviving echoes of the Intelligence had manifested at the point in 1630 when the Doctor met Padmasambhava, or an earlier one, and from there began its plan with the robot Yeti and Padmasambhava in Tibet.