Possible Clues:

• Extensive plain without trees
• Unforested plain
• You'd need long legs to make so long a pace, by the sound of it
• Looking back, record dogs and cats in one flat space in Russia
• Dictator's rung for location of gulags
• Badly set university course, that's plain
• Sort of plain
• Siberian grassland
• Treeless Siberian tract
• Russian prairie