Like I said, alters have been found with both ephedra and cannabis. Also poppy.
The argument against cannabis is that it's so pervasive and was so well understood as a psychoactive in India that it seems odd that so many of the ancient reference texts express confusion about soma's identity: those authors *did* know bhanga, and yet soma was still treated as something separate and mystical.
On the other hand--most wild cannabis looks nothing like the hydroponic of today.... Obviously. But there are/were wild strains that are more "exotic" looking, with larger buds and more crystalization on the buds. "Soma" just meant the "food of the gods" and clearly the actual plants used tended te vary by region and time period--as demonstrated by the archeological evidence--but where soma might have referred to cannabis, when referred to by ancient scholars that already *knew* of cannabis... It may have been referencing particular cultivars. Thus that line in the Vedas that specifies the best soma coming from beyond Kashmir.
It also must be noted that many Indian scholars agree that it's probably cannabis. Or at least that cannabis was probably *one of the substances* referred to as Soma.
But... Ephedra does not produce effects equivalent to ephedrine. Keep that in mind. There are different species of ephedra, and even of the species that contain ephedrine, there are other alkaloids present. But even so... I don't know why you or anyone thinks that this "soma" *must* have been an entheogen and the inspiration for all the creativity of the Indo-European religious and cultural practice. Mere "stimulants" are consistently valued across cultures and given sacred, spiritual value. It makes perfect sense: from the perspective of a scientifically illiterate but spiritual culture, what plant might embody life itself? A plant which invigorates the self, which gives energy, gives "*virulence*", even gives sexual energy and thus can be connected with the myths surrounding fertility and surrounding the act of creation itself.
The traditional Chinese pharmacopeia is extensive, but a a glance, what plant is given the most respect, is the basis of formal ceremonies, conducted by and for everyone from te emperor down to many of the poor locals? Tea, of course. Camilia Sinensis. why? Sure it tastes good. And sure, it has all kinds of health benefits--many of which were discovered, or otherwise attribute to it, by the people who respected and used it in China, Korea, and Japan. What would compel this use? At the most primordial level, before the tea ceremony had already become an enshrined cultural practice, what would cause tea to stand out as a particularly special plant? It's a stimulant. It invigorates the mind and the body.
Similarly, for Native North Americans, there was a plant used ubiquitously, so much so that it could form the core of a ceremony performed to demonstrate peace between tribes: what was it? Tobacco. A stimulant. Look a little farther south, then, and what do you see? "Chocolate" drinks prepared from the cacao bean--not your sweet-tasting, relaxing store bought milk chocolate, but rather a bitter mixture full of caffeine and theobromine and theophylline and phenylethylamine.
Further south still and you've found yourself the coca leaf--and I hope you don't claim that that was never considered a "sacred" plant, because it certainly was, and still is.
The very earliest evidence of coffee drinking comes from the Sufi shrines, where it was regarded as a sacred for its ability to allow them to dance and study far into the night. Tobacco also found a place in Islamic culture, and became an important part of their artistic expression--intricate water pipes and complex ways of preparing the tobacco (as shisha).
And for all the talk about use of entheogens by Native American groups: of ayahuasca, of bufotenin, and of mescaline, let's not forget that one of the most sacred plants in South American tribal legend--presented as a gift from the gods directly to a man who saved their lives, as a "drink of friendship"--is Yerba Mate. There's caffeine again! Besides, mescaline is classed as an entheogen today--and it most definitely is--but it's also very distinctly notable for effects beyond that: it provides many hours of boundless physical energy coupled with a calm, contemplative, even languid, state of mind. Well, there's one thing in particular it was famously used for: allowing messengers to run for miles without fatigue.
Hell. alcohol "invigorates the body" too: Sure, it's a depressant, but it causes significantly higher adrenaline levels than even cocaine or amphetamine--and it flushes the skin and provides (the sensation) of warmth, and creates false courage and "drunk muscles" through disinhibition. Well alcohol has certainly played an important part in the religious custom of many a culture--forget the Christian sacrament: by that time it was too old and too established. How about the old Viking tradition of drinking fermented goat's milk before they went into battle? Or the old term (I believe still used in France) Aqua Vitae "water of life" for all alcohol in general but more specifically originating as a term for the spirits derived produced by a monastery from the extensive distillation of fruit wine to produce a near-neutral grain alcohol.
Ok... I'm sure I could keep finding more examples but this is turning into a tangent and I think it's starting to make my point less clear rather than more clear. My overarching point is that stimulants have always been viewed as sacred plants, frequently a gift of the gods, and often become deeply embedded in a culture with the development of complex ritualized use patterns. They are often described in texts in very spiritual terms, and though some (mescaline obviously, but also cannabis, tobacco, and even ephedra) have other mind-altering properties, there is a frequent focus on their ability to invigorate the mind, body or soul. I think it's perfectly sensible that, to a culture utilizing a "God of the gaps" type theology/spirituality, the ability of a plant to impart energy, the sensation of being alive would place that plant in a very special place. As a food for the gods, for example.
I'm of the opinion that--among the early Aryan tribes who brought te Vedas to India--ephedra probably predates cannabis as a holy plant, simply because they likely had the opportunity to use it earlier in their migration, farther north, before they had the opportunity to use cannabis. Maybe they used Amanita too, even farther north. In fact they probably did. But it doesn't match the descriptions in the Vedas. Ultimately it becomes a question of semantics: all of these plants were used in religious rituals, which one we can call the "real" soma is going to be somewhat arbitrary, considering that the term has clearly been used to describe different plants in different time periods and regions.