I have found sweaters to be the most challenging to find in tall sizing. Even brands that have liberally offered tall sizing in the past (looking at you J.Crew), I have found to never consider tall sizing when it comes to sweaters. Earlier this week, I bitched about not being able to find tall cashmere. Lo and behold, I found tall cashmere crewnecks, turtlenecks, and cardigans and each style in a ton of colors. You are welcome.
Additionally I found a few sweaters available in tall, though not in one hundred percent cashmere, each with fabric content did not make me immediately want to hurl.