The Celts arrived in the wake of the Roman withdrawal at the end of the fourth century.
( ( The Celts ) ( ( ( arrived ( in ( ( the wake ) ( of ( the ( Roman withdrawal ) ) ) ) ) ) ( at ( ( the end ) ( of ( the ( fourth century ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NNPS Celts)) (VP (VBD arrived) (PP (IN in) (NP (NP (DT the) (NN wake)) (PP (IN of) (NP (DT the) (NNP Roman) (NN withdrawal))))) (PP (IN at) (NP (NP (DT the) (NN end)) (PP (IN of) (NP (DT the) (JJ fourth) (NN century)))))) (. .)))
At the end of the fourth century was when baked goods flourished.
( ( At ( ( the end ) ( of ( the ( fourth century ) ) ) ) ) ( ( was ( when ( ( baked goods ) flourished ) ) ) . ) )
(ROOT (SINV (PP (IN At) (NP (NP (DT the) (NN end)) (PP (IN of) (NP (DT the) (JJ fourth) (NN century))))) (VP (VBD was)) (SBAR (WHADVP (WRB when)) (S (NP (JJ baked) (NNS goods)) (VP (VBN flourished)))) (. .)))