thousands; several thousand
Refers to an approximate number in the low thousands, typically between 2,000 and 9,000. Used as a noun or prenominal modifier.
数千人の観客がスタジアムに集まった。
Several thousand spectators gathered at the stadium.
This project will cost several thousand dollars.
Thousands of fans gathered for the concert.
You can buy this bag for a few thousand yen.
Several thousand parts are stored at the factory.
This ruin is believed to have been built several thousand years ago.
数千 refers to a quantity in the low thousands, whereas 数万 refers to a much larger quantity in the tens of thousands.
数千 means 'thousands', a smaller scale than 数万, which means 'tens of thousands'.
数百 means 'several hundred', while 数千 means 'several thousand'—an order of magnitude larger, so learners can confuse the two similar-looking words.
Compound of 数 (すう, 'several') + 千 (せん, 'thousand'). The reading すうせん follows standard on'yomi.