How did mankind travel through the warp during the Great Crusade?

Question

In his current state, the Emperor of Man on his Golden Throne generating the psychic beacon called the Astronomican which makes warp travel possible.

The Astronomican is a psychic beacon which the Navigators utilise to pilot the spaceships of the Imperium through the otherwise unnavigable chaos of Warp-space. [1]

But what about the time of the Great Crusade?

Thousand of worlds were conquered throughout the galaxy in a period of 200 years, so mankind MUST have had the means to warp travel and with the Emperor moving around he could not have generated a fixed psychic beam that would make navigating through the warp possible, even if he would be strong enough to do that without the Golden Throne.

Is there a canon explanation for how mankind traveled through the warp during the Great Crusade?

Sources: [1] http://wh40k.lexicanum.com/wiki/Astronomican

Answer 1

Travel was accomplished by using the same Immaterium-skimming technology used during the expansion of the Imperium in its early days.

• This unnamed technology did not require the direct use of the Warp but was affected when Warp Storms became problematic. This technology was slow, dangerous and inefficient, made more so by the ending of the Warp Storms after the Fall of the Eldar.

• It was this instability and inefficiency which led to the development of the Astronomican, to hasten the return of Imperium forces to worlds stranded for 5,000 years during the Age of Strife

It is uncertain how faster-than-light travel was done in the Dark Age of Technology before the Astronomican existed, though it can be safely assumed that a form of faster than light travel that is non-dependent on entering Warpspace and may be similar to Necron phase drive technology was used. Warhammer 40K Wikia -> Astronomican

Dark Age of Technology (M15-M25)

• This was a period of 10,000 years of faster than light travel when Humanity first learned to skim the surface of the extra-dimensional region called the Immaterium. Using the Immaterium, Humanity was now able to travel much farther and more accurately than it had ever before.

Much of the era of human history known to Imperial historians as the Dark Age of Technology that lasted between approximately the 15th Millennium and the 25th Millennium is mysterious. It was in this time that the psychic mutants called Navigators were first born, and combined with the invention of the Warp-Drive, allowed humanity to travel between worlds faster than the speed of light by using the dangerous hyperdimensional, psychically-reactive medium of the Immaterium or Warp. The existence of rapid interstellar travel allowed human colony worlds to interact on a normal timescale for the first time and interstellar commerce and communication became possible, allowing like-minded human worlds to join into political and economic combines for their mutual benefit. -- Warhammer 40K Wikia Timeline of the Warhammer 40K Universe

• This brought about the Age of Technology, where new technologies and social transformations spread Humanity everywhere their ships could reach. During this time, humanity had even come into contact with alien races and established treaties of non-aggression. These would eventually be destroyed with the coming of the Age of Strife in the 26th Century.

After The Age of Strife

• From M25 to M30, Humanity was unable to use their drive technology to skim the surface of the Immaterium due to destabilizing warp storms. At the Fall of the Eldar, when Slannesh was created, the Warp Storms which had inhibited Mankind from traveling through warp space for 5,000 years ceased.

• Mankind returned to the slow warp technology the used before the Warp Storms, blind jumping across the galaxy. But it was determined this would be very dangerous and much slower than the Imperium was used to, so a fix was needed and the concept for the Astronomican was created.

The Great Crusade M30

The Great Crusade of the Emperor of Mankind began as the Age of Strife came to an end for humanity. The Warp Storms isolating the human colony worlds for 5,000 Terran years had finally disappeared with the birth of Slaanesh and the Fall of the Eldar in the 30th Millennium

• During the Great Crusade, the Astronomican was activated initially by the Emperor, and powered by his psychic ability. The Astronomican was developed to extend the range of the Navigators when they jumped giving them a psychic marker to reference at all times. This permitted much longer jumps and more stable jumps.

At the time the Astronomican was the single largest artifice on Terra, and the entire device was merely a focus through which the Emperor could direct His fathomless psychic energies to generate a partly self-sustaining telepathic signal through the Empyrean (although few were aware of this fact). Later the Golden Throne was connected and the comatose Emperor continued the generation of the Astronomican. Warhammer 40K Wikia -> Astronomican

Also See Stackexchange Article: The Spread of the Imperium of Man