In this SciFi SE answer to "Can we date the technology in the Lord of the Rings movies?" , I made a statement that I wasn't able to research as fully as I'd have liked, and therefore would like a confirmation of whether historical research supports it.
Gunpowder used to blow up the wall at Helm's Deep - the earliest invention is in China, 6th to 9th century. But it was not used for explosives back then IIRC - the first mention of the use of black powder for explosives I could find was Dicovery Channel's (un-cited) mention of 12th century in China. The first use of black powder as explosive (as opposed to projectile propellant) in Europe eludes me but it wasn't used for civilian purposes (mining explosives) till 17th century.
So, the questions are:
Is there a confirmed source indicating the use of black powder for military purpose explosives as early as 12th century AD in China (as in, to blow stuff up instead of to propel something)? Are there no references to earlier use?
What was the earliest confirmed such use in Europe? (other regions matter less since Isengard seems to be a Europe equivalent in Tolkien kinda-geography, situated north of Gondor)
As Lennart correctly surmised, I was thinking of the use of black powder for demolition type effect (as was done in LOTR), NOT as an explosive in a shrapnel-producing grenade/bomb.