When I watch movies about medieval Europe, or Asia around this time for that matter, we see that the punch of a bow and arrow is enough to kill a grown man at once. They can penetrate armor, go straight through the bodies of soldiers, knock people to the ground, etc. However when I watch documentaries of hunters in different tribal, and less-tribal societies, in the modern world, in Africa for example, we see that their arrows will barely stick in the body of an animal and they need to either pepper the animals with arrows or use poison to kill it, and even then it takes them often hours of chasing the wounded animal to catch it. So my question is how much is the strength of the medieval bow and arrow a dramatization of Hollywood? Was it more alike the bows of these current tribal societies? Or did the 'superior' technology of the medieval Europeans give them extremely strong bows?
In terms of putting numbers to the Medieval European bow draw weights, most of our info comes from reconstructions of finds. These are predominantly tabulated in Jurgan Junkmanns' 'Pfeil und Bogen Von der Altsteinzeit bis zum Mittelalter' which is pretty much the bible of pre-modern archery-archaeology (even if it does miss a few finds and it is in German). Paulson and Johann Tiennes have also contributed and Stephen Fox has been filling in the blanks in Viking Age Ireland with his Masters/PhD work but I haven't seen the papers so can't add their results. There is also a vast number of amateur bowyers that work in researching and reconstructing these things but they’re a bit hard to cite (the Paleoplanet forums is where you’ll find them though).
Most of the finds he and others have reconstructed are of complete bows (so primarily the 9th-11th cent. Hedeby bows, the 7th cent. Oberflacht bows for early medieval and lots of pre-historic ones) as the exact dimensions and timber of similar quality is needed, thus not having the total length of the bow can drastically alter the expected draw weight (shorter bows with the same limb width/thickness have comparatively higher draw weights than similar longer bows, a technique known as 'spiking' when shortening limbs to up the poundage).
Note though, that we only have 7-9 complete or near-enough complete finds to replicate for AD 700-1400-or so in Western Europe (Balinderry, Waterford, Dublin, Burg Elmendorf, Wassenar/Leiden, Pineuilh la Mothe and Hedeby/Haithabu, potentially also Adare/Desmond Castle and Susaaen/Sjalland but I can’t get good enough references for them) out of 31 (or 33) fragments, so the reconstructions aren't statistically great for making generalisations and Hedeby/Ballinderry/Wassenar are actually potentially outliers in terms of length and style for approx.-10th cent. bows so generalisations based on them are even worse (the others are all approx. 160 or sub-160 cm with an intermediary flatbow/longbow design, not the ‘typical longbow’).
Anyway, Junckmanns’ first Hedeby replicas come out at 1.79m/77lb, 1.7m/73lb, 1.68m/55lbs when done in Elm, his Oberflachts are 1.72m/52lb, 1.71m/57lb, 1.58m/61lb also in Elm (with +-35% error margin). A reconstructed Aalsum bow comes in at 1.6m/79lb and Paulson’s estimation on the Hedeby 1 bow is cited as 80-100lbs with a 70cm draw. In-the-style-of pieces also tend to come in at about 70-80lbs.
An amateur bowyer on Paleoplanet had an attempt at the Wassenar and got about 100lbs with a 160cm bow, 26 inch draw. (Draw length is also important as draw weight scales proportionately to it, I apologise for not being able to reference it properly above as my e-book copy is playing up).
It is assumed that Adare may have been significantly lighter based on the dimensions. Many of the pre-historic bows also come out at sub-50lbs.
There’s nowhere near enough of most of the Dublin/Waterford bows to recreate but the two surviving ones are short and thick, as are Burg Elmendorf and Pineuilh.
This is almost entirely context-less though- we have little idea whether these were the standard draw weights or what they were used for. They may have been specific war bows with lighter ‘normal’ hunting bows. Or the lighter bows we see may be for kids and these were the standard draw weights. It’s not clear and we need more context, which probably won’t just come from the finds, and the textual evidence is also lacking in specifics.
Why’s context important? Because while technology certainly provides limits on what can be done, cultural practice also shapes what people make and use. Hunting isn’t always about using the most powerful bow possible, it can be about using the skills developed and revered in the culture and bows which suit that hunting style. There’s nothing wrong with stalking to short distance and then shooting, it’s just a different way of working. So while there may be technological reasons for how African bows developed (brittle wood, small stave sizes, bad grain etc) there may also be social reasons, but you’d have to ask an anthropologist (or the suitable academic role) about that.
Sources:
Junkmanns, Jürgen (2013) Pfeil und Bogen: Von der Altsteinzeit bis zum Mittelalter. [Bow and Arrow: From the Paleolithic to the Middle Ages]
de Stoute, Jur (2008) Paleo Planet, Archery - Primitive Bows - 1200 year old longbow from Netherlands. (Website Article)
See also (if you can get your hands on them):
'Pfiel und Bogen in Haithabu'. In Geibig, A. and Paulsen, H. (1999) Neue Ausgrabungen in Haithabu; Band 33: Das archäologische Fundmaterial VI. Ausgrabungen in Haithabu. Hedeby-Ausgrabungen in Haithabu Lansac, Pierre (2008) 'Les arcs de Pineuilh (Gironde)'. [The bows of Pineuilh (Gironde)]. Des amis du musée de l'archerie et du Valois, n°7, février 2008,pp 2 à 8.
Halpin, Andrew (2008) Weapons and Warfare in Viking and Medieval Dublin. Medieval Dublin Excavations 1962-81: Ser.B Vol.09
Hamm, Jim. The Traditional Bowyer’s Bible, vol 3. Covers North American and African traditional bows.
Edit: reformatted the sources