Prada/Miu Miu were pretty big on that kind of stuff around 1999-2000. The SS99 and FW99 collections have lots of sling bags/fanny packs/belts variations, big emphasis on functionality, uniform-likes somewhat repetitive collections with limited and drab color palettes (greys, greens, beiges) and lots of synthetic/tech fabrics and sportswear inspired elements (plastic buckles and drawcord toggles fastenings, some jackets even have slings like Acronym and RO). They're a great example of Prada's brand of minimalism and sit somewhere between Jil Sander and Helmut Lang collections of the time.
The shorts I wanted to wear today didn't have pockets so I broke out the bum bag/fanny pack to hold my wallet and phone. I forgot how convenient these things are. Looks stupid since I'm wearing a backpack at the same time; but screw it.