Which three specific working dog types influenced the foundation stock of the Yorkie?

Black and Tan Terrier, Paisley Terrier, and Waterside Terrier

Tracing the exact lineage of the early Yorkshire Terrier is challenging because documentation focused on working ability rather than formal pedigree. However, accepted history points to a combination of several distinct working terrier types prevalent at the time. The Black and Tan Terrier, which is a predecessor to the modern Manchester Terrier, contributed to the gene pool. Also significant were the Paisley Terrier, sometimes referred to as the Clydesdale Terrier, and crucially, the Waterside Terrier. The Waterside Terrier was specifically valued for its rough coat and proven skill in capturing water rats, thereby lending necessary terrier spirit and hunting proficiency to the emerging breed line.