▁surv ives ▁to ▁the ▁present ▁day ▁and ▁time ▁travel ▁to ▁the ▁past , ▁such ▁as ▁the ▁" Company " ▁stories ▁of ▁K age ▁Baker . ▁There ▁are ▁authors ▁who ▁write ▁in ▁both ▁sub gen res , ▁like ▁Harry ▁T urt led ove ▁in ▁his ▁Tim eline ▁ 1 9 1 ▁series ▁and ▁" The ▁G uns ▁of ▁the ▁South " ▁novel , ▁respectively . ▁Isaac ▁As im ov ' s ▁short ▁story ▁What ▁If -- ▁is ▁about ▁a ▁couple ▁who ▁can ▁explore ▁alternate ▁real ities ▁by ▁means ▁of ▁a ▁television - like ▁device . ▁This ▁idea ▁can ▁also ▁be ▁found ▁in ▁As im ov ' s ▁ 1 9 5 5 ▁novel ▁The ▁End ▁of ▁E tern ity . ▁In ▁that ▁novel , ▁the ▁" E tern als " ▁can ▁change ▁the ▁real ities ▁of ▁the ▁world , ▁without ▁people ▁being ▁aware ▁of ▁it . ▁ ▁There ▁is ▁also ▁a ▁historical ▁fant asy ▁sub gen re . ▁P oul ▁Anderson ▁has ▁a ▁number ▁of ▁historical ▁fant asy ▁nov els ▁set ▁in ▁Vik ing ▁times ▁ ▁including ▁The ▁Bro ken ▁S word ▁and ▁H rol f ▁Kra ki ' s ▁S aga . ▁Otherwise ▁space ▁opera ▁author ▁C . ▁J . ▁Cher ry h ▁has ▁a ▁whole ▁historical ▁fant asy ▁series ▁The ▁Russian ▁St ories ▁set ▁in ▁Med ieval ▁K ie van ▁Rus ▁times . ▁Guy ▁G av riel ▁Kay ▁has ▁number ▁of ▁historical ▁fant asy ▁nov els ▁as ▁" The ▁L ions ▁of ▁Al - R ass an " ▁set ▁in ▁Renaissance ▁Spain