Hearing people talk about cryptocurrency as a digital asset, made me think how was this asset manufactured?
Cryptocurrency is a broad term for an industry, and it has many cryptocurrencies in this branch industry. It's not too rightly by generalizing that cryptocurrency is a digital asset.
It turned out David Chaum's effort to enable anonymous transactions led to the introduction of ecash, in 1990. This is an easy find, it doesn't take much look to get information.
You can read some documents about Bitcoin prehistory and some projects created before Bitcoin in 2009.
Bitcoin Preshitory (Saylor.org Academy).Bitcoin prehistory.Bitcoin prehistory tree.Bitcoin and cryptocurrency technology (Princeton Universtiy Press). It's a draft and if you want to get a complete book, download it
there.