"Beyond the Black River" does contain the term borderer, border-man, -men, woodsman, woodsmen, frontiersman, forester and the like:
"'The demon isn't going to get Tiberias' head if I can help it,' he growled. 'We'll carry the body into the fort. It isn't more than three miles. I never liked the fat fool, but we can't have Pictish devils making so cursed free with white men's heads.' The Picts were a white race, though swarthy, but the border men never spoke of them as such. Balthus took the rear end of the litter, onto which Conan unceremoniously dumped the unfortunate merchant, and they moved on down the trail as swiftly as possible."
"'Some kind of devilment,' muttered the forest runner. 'They might have gathered here to watch Zogar's magic-making. He'll make some rare magic with our carcasses. Well, a border-man doesn't expect to die in bed. But I wish we'd gone out along with the rest.' The wolfish howling of the Picts rose in volume and exulta- tion, and from a movement in their ranks, an eager surging and crowding, Balthus deduced that someone of importance was coming."
"Conan reached his long arm for the wine-jug. The forester stared at him, compar- ing him with the men about them, the men who had died along the lost river, comparing him with those other wild men over that river. Conan did not seem aware of his gaze. 'Barbarism is the natural state of mankind,' the borderer said, still staring somberly at the Cimmerian. 'Civilization is unnatural. It is a whim of circumstance."
"Not even a Pict could trail them over naked rock. 'How did you get away?' he asked presently. Conan tapped his mail-shirt and helmet. 'If more borderers would wear harness there'd be fewer skulls hanging on the altar-huts. But most men make noise if they wear armor."
"Lifting his head as he licked his livid lips, he muttered, making himself heard with difficulty above the fiendish clamor of the Picts: 'So they got you, too!' 'Sneaked up in the water and cut the other fellow's throat,' groaned Balthus. 'We never heard them till they were on us. Mitra, how can anything move so silently?' 'They're devils,' mumbled the frontiersman. 'They must have been watching us from the time we left midstream. We walked into a trap. Arrows from all sides were ripping into us before we knew it. Most of us dropped at the first fire."
"The shaman was talking now, a harsh, guttural intonation that yet carried the hiss of a cobra. He thrust his head on his long neck toward the wounded man on the stake; his eyes shone red as blood in the firelight. The frontiersman spat full in his face. With a fiendish howl Zogar bounded convulsively into the air, and the warriors gave tongue to a yell that shuddered up to the stars. They rushed toward the man on the stake, but the shaman beat them back."
These examples should suffice for now...