Short answers, pulled from the story.
The first mention of the Arkhangelsk Astrakhan line appeared on the 18th of December 1940 in Führer Directive 21. This document outlined the specific goals and conditions for the German invasion of the Soviet Union.
General Erich Marcks shaped the initial thinking during the summer of 1940 with his report known as Operation Draft East. His plan advocated occupying territory up to a line stretching from Arkhangelsk to Gorky and Rostov.
German planners calculated that reaching the A, A line would deprive the Soviet Union of around 86% of its petroleum assets. They assumed most military supplies existed west of the proposed boundary while food production and population potential were also concentrated there.
Marcks believed capturing Moscow and areas beyond it would take between nine and seventeen weeks. He argued that holding this line would prevent future threats from the east and protect Germany against enemy bombers operating from Soviet soil.
The failure to achieve any part of the designated territory reflected flawed assumptions about speed and endurance. Winter conditions slowed German progress significantly compared to original estimates and logistical failures doomed the operation before completion.