We have decomposed the broad Hα, Hβ and Hγ lines of 
90 Active Galactic
Nuclei (AGNs) into a superposition of a very broad and 
an intermediate Gaussian
components and discovered that the two Gaussian 
components evolve with
FWHM of the whole emission lines. We suggest that the 
Very Broad Gaussian
Component (VBGC) and the Inter-Mediate Gaussian 
Component (IMGC) are
produced in different emission regions, namely, Very 
Broad Line Region (VBLR)
and Intermediate Line Region (IMLR). The details of the 
two components of Hα,
Hβ and Hγ lines indicate that IMLR has a flattened 
geometry, is more dense and
dusty compared to VBLR. Our results indicates that the 
radius obtained from
the emission line reverberation mapping normally 
corresponds to the radius of
the VBLR, but the radius obtained from the infrared 
reverberation mapping
corresponding to IMLR, i.e., the inner boundary of the 
dusty torus. The existence
of the IMGC may affect the measurement of the black 
hole mass in AGNs.
Therefore, the deviation of NLS1s from the M-sigma 
relation may be explained
naturally in this way. The evolution of the two emission 
line regions may be
related to the evolutionary stages of the broad line 
regions of AGNs from NLS1s
to BLS1s. Based on the results presented here, a 
unified picture of hierarchical
evolution of black hole, dust torus and galaxy is 
proposed.Re-examination of 
the reverberation mapping data provide supportive 
evidence for our model.