For hundreds if not thousands of years, the making of hashish was a hands-on job, like making bread. The process often began with rubbing the flowers between the hands until they were covered with a sticky mass of trichomes and resin. What you then scraped off your hands and pressed into shape (preferably with a little heat), was black hashish - bruised and crushed, colored by the oils in human skin. The other time-honored technique involved dry-sieving your weed - a cloth over a pan is one no-frills method, and a method yielding happier trichomes - followed by being heated and pressed as with the hand method.
All of this gets you noticeably stronger stuff than a pipeful of weed - but most often no stronger than around 40-50% THC, compared to the 24-28% figure which is currently the top range available from smoking flowers. To manage the astronomical THC content of today's medicinal cannabis concentrates - as much as 90-95% - requires considerably more sophistication and gear that looks like it came off of a space ship. At this level, enough of the original methodology has been left behind that it's really not "hashish" anymore, although the word will probably stick around out of tradition.
The next technological advance would have been the making of cannabis infused fats, utilizing the oils in butter or other kind of cooking oil combined with heat to extract the THC. Strain out the weed roughage after boiling and simmering for a couple of hours and bake some cookies with it!
Ice water hash, is another basic method involving simply tossing a bunch of very thoroughly dried weed into an ice chest or bucket of ice water. Leafage is light and floats, hash is heavy and sinks to the bottom. Scoop out the vegetable material, sieve the liquid through a coffee filter and voila! The beauty is the low-tech nature of these methods. You can do them at home, although very large quantities of weed are necessary to make a comparatively miniscule quantity of hash.
This all changed with the dawn of the Medical Cannabis Era. There are stories that pioneers in California were experimenting with making bubble hash back in the sixties, but real modern medical concentrates didn't appear in earnest until it became viable - not to mention legal - to drop a large wad of cash for the sci-fi hardware that is now required. New terminology began to appear - budder, honey oil, wax, shatter… BHO and solvent extraction, CO2 extraction, all began to produce concentrates with astonishingly high THC content - patients suffering from chronic pain could now take large doses of medication which better relieved their suffering, sometimes with only a few puffs of the vaporizer.
One of the newest developments, with ties to the whole plant way of thinking, is Live Resin. This involves flash freezing the entire, newly harvested plant, preserving complete profiles of terpenoids and cannabinoids that would normally degrade rapidly. This preserves and offers a complete experience, recalling the original plant, when eventually vaped or dabbed, providing enhanced flavor, aroma and potency to medical cannabis patients.
The final Live Resin extract can be produced via either BHO or CO2 extraction, but, as a result of the higher terpene content, tends to want to be gooey, rather than firming up like shatter or glass. Unfortunately, one of the drawbacks is that it's not as stiff as some of it's cousin concentrates. It's also harder and more expensive to make, and requires processes far beyond your kitchen… not a homebrew product, this Live Resin. But it offers as much as 95% THC content, enough to deliver a massive dose of medication to those in need.
The most interesting aspect of all this is that it's still very much a work in progress and many discoveries in Cannabis concentrates still lie before us.