It has happened more than once Antaeus. Wise ones in ancient Lemuria left before the cataclysm that destroyed the continent (and most of the population of the earth) taking the ancient wisdom to higher ground in the Himalayas and elsewhere. That brotherhood (most of whom were perfected Adepts) have been responsible for seeding the wisdom teachings into the consciousness of the human race for tens of thousands of years. What have become the main religions of the world (some of which are long gone) were originally inspired through that brotherhood. They guide and guard and have planted seeds of truth over the millenia to bring us to this opportunity where again we can ascend into spiritual planes of reality. In the past, as soon as those seeds began to sprout green shoots they were set upon by dark controlling forces in order to distort the original intent of the spiritual teaching. That is why the spiritual brotherhood never sleep.... because their good work keeps getting distorted by the enemies of truth. The true Adepts continue to seed our culture with ideas from the culture of Lemuria, which in ancient times rose to a high degree of spiritual / material perfection before the rot set in and the continent went down in flames. A golden age of enlightenment flourished there for millenia before the fall. Some of the early root races (according to Blavatsky?) ascended after incarnating on Lemuria. They fulfilled their divine plan in materiality without falling into duality consciousness and ascended back to spirit. That was very ancient times and we're talking millions of years. Aparantly it was the 4th root race which fell into 'duality consciousness' and are still here on earth trying to re- integrate with the spiritual self and ascend out of the lower planes of matter.
Not only that but, from my understanding, a rescue mission was undertaken to re- ignite those fallen souls with the fire of spirit which they had lost their conscious connection to. All of Earth's inhabitants were living in total darkness at that time. A large number of highly evolved souls, including Jesus, came to Earth to keep the spiritual flame alive for fallen humanity and they arrived at a 'beach head' called Shamballa in central Asia. They did not come to earth in spacecraft but incarnated into subtle earth bodies without the usual method of sexual reproduction. (See Edgar Cayce's 'Atlantis" material for descriptions of non- sexual reproduction). Others among them did incarnate into physical bodies. They came to earth via the etheric realms of Hesperus "the love star".... Venus. But eventually after successfully raising some among humanity, many of the rescuers also fell into duality consciousness. Jesus was one of the souls who fell into duality but, being of greater attainment than most, he has never lost the conscious realisation of his divine identity and origin all this time. Over his many incarnations on earth the Adept we now call Yesua / Jesus has continued to work for the rescue, now of his brothers and sisters from the original rescue mission, and also for fallen humanity he originally came to help. He has succeeded in that to some degree and many of his brothers and sisters have risen from earth (in that ancient ritual called 'ascension') and today work with him in higher octaves on our behalf. They work inspirationally and occasionally they materialise a physical body for certain purposes. [That is why NESARA and SANANDA / Galactic federation and other similar scams float, because the general theme has some basis in reality].
It wouldn't really be an exaggeration to say that a cosmic tragedy is unfolding on planet earth. Add to this the soulless humans and the recalcitrant fallen angels incarnate and you get an idea of why Earth has been called a crossroads for many souls at very different stages of spiritual evolution and from many different places non- indigenous to earth. It is this soul knowing (regarding that truth) that the so called "space brothers" in their "spacecraft" play apon when they insinuate themselves into the role of "Saviors of Humanity".
There is legend that one of Jesus' incarnations was on Atlantis at one time ~ 35,000 yrs ago. This was before Atlantis broke up (in 3 stages over tens of thousands of years) and finally sunk about 9 or 10,000 BC. He was emperor and Adept and under his wise tutelage ~ 1,000,000 souls ascended in that wave. Since then a few more souls have also ascended and the cycle has turned again where the opportunity has arrived for the ascension of many souls again. The ascension is an opportunity, it is not a guaranteed, forgone conclusion. The earth is rising in vibration but we must rise with it by internalising the new vibration. The earth is being purged by that rate of increase and so must we be in the depths of our subconscious. So, the question ... "what must we do to ascend" is vital. We must do what all who have already ascended have done. Seek and find the "inner kingdom" which our ancient brother came to remind us AGAIN ~2000 yrs ago. The inner- spirit of our original divine identity will cleanse our souls (and the 4 lower bodies) of all "sin" ... all negative karmic energy... clogging the subconscious regions of our chakras and subtle bodies. This spiritual light will enter into us consciously and raise our personal vibration 'FRV' to such a high degree that we will easily transcend the gross vibrations of duality consciousness....ie easier than past ages since the last wave.
Earth is tilted on it's axis due to the heavy weight of fear and agression dumped into the lower planes by a half crazed humanity over aeons of time. What we must do to ascend is let the "river of life" flow through us once again and thereby transmute the dams in our own subconscious which separate us from each other and from the Earth. If we will do this the planet can also be relieved of the dark energies which could otherwise tilt the earth beyond the point of no return, resulting in pole shift. The light energy that can come through ourselves is greater than the darkness of the mass consciousness in opposition.
The nazarean master said ... "He that is in you (the light of the inner- christ and I AM Presence)
Is greater than he that is in the world (the darkness of the ego and
the egoistic mass conscioiusness)
We are now embodying the light, this magnetic urge to wholeness, and we will succeed in making the most of this opportunity for ascension with a minimum of destruction to the platform we need in order to make it all happen. We are the key to success in all this and it is not just a personal victory we are accomplishing.
But our personal oneness with inner- spirit is all we will ever need as a guide through the higher planes. It is not essential to pre- map our way beyond the physical plane if we can develop a strong intuitive connection to the higher- Self in this life. It will be the "rocket fuel" through the astral and lower mental planes and it will thrust us through into the upper etheric realms, from where we will prepare for the ultimate permanent wedding of the soul to spiritual Selfhood..... the ascension.