  We searched for shocked carbon chain chemistry (SCCC) sources with C$_3$S
abundances surpassing those of HC$_5$N towards the dark cloud L1251, using the
Effelsberg telescope at K-band (18 -- 26\,GHz). L1251-1 and L1251-3 are
identified as the most promising SCCC sources. The two sources harbor young
stellar objects. We conducted mapping observations towards L1251-A, the western
tail of L1251, at $\lambda$ $\sim$3\,mm with the PMO 13.7 m and the NRO 45 m
telescopes in lines of C$_2$H, N$_2$H$^+$, CS, HCO$^+$, SO, HC$_3$N and
C$^{18}$O as well as in CO 3--2 using the JCMT. The spectral data were combined
with archival data including Spitzer and Herschel continuum maps for further
analysis. Filamentary sub-structures labeled as F1 to F6 were extracted in
L1251, with F1 being associated with L1251-A hosting L1251-1. The peak
positions of dense gas traced by HCO$^+$ are misaligned relative to those of
the dust clumps. Episodic outflows are common in this region. The twisted
morphology of F1 and velocity distribution along L1251-A may originate from
stellar feedback. SCCC in L1251-1 may have been caused by outflow activities
originated from the infrared source IRS1. The signposts of ongoing SCCC and the
broadened line widths of C$_3$S and C$_4$H in L1251-1 as well as the
distribution of HC$_3$N are also related to outflow activities in this region.
L1251-1 (IRS1) together with the previously identified SCCC source IRS3
demonstrate that L1251-A is an excellent region to study shocked carbon chain
chemistry.
