[adventured]

> Until Google monopolized it, search engines and ad networks were independent pieces competing on an open market

It was always a mixture of both scenarios.

Yahoo prior to using AltaVista, Inktomi or Google had its own search tech - going back to 1995 - and its own advertising network.

AltaVista had its own search tech and its own ad network.

Lycos, a top 5 portal at the time, had its own search tech and its own ad network.

GoTo.com, very popular in its day, was both a search engine (acquired) paired up with its own famous ad system.

For several years AOL flirted on & off again with their own search tech, initially based on WebCrawler, prior to and after their deal with Excite. They also ran their own ad network.