Well met. I have been long from faire Faerun, and my memories often serve me more poorly than I would like.
(I recall that their was once a "pegasus ranch" in the Western Heartlands. Is this correct, and where can i find futher details on the topic? Thanks alot!)
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You could be thinking of Aluena Halacanter'a estate, of Boareskyr Bridge, as referenced in Volo's Guide to the Sword Coast. It's noted that rich merchants often seek out this sorceress who raises pegasi on her home soil.