Mapproxy generating plain tiles using mapnik

I am using MapProxy 1.12 and Mapnik 3 for map creation.
Plain tiles are genererating, no map. Some tiles are showing 404 error(The requested tile is outside the bounding box of the tile map.).
sample.yaml

services:
  tms:
    use_grid_names: true
    origin: 'sw'
layers:
  - name: district
    title: District Layer
    sources: [dist_cache]

caches:
  dist_cache:
    grids: [distgrid]  
    sources: [dist_tms]   

sources:
  dist_tms:
    type: mapnik
    mapfile: /var/www/Mapfiles/district.xml  
    layers: district
    transparent: true

grids:
    distgrid:   
        base: GLOBAL_GEODETIC
        srs: 'EPSG:32643' 
        bbox: [291627,904686,958569,1426831]   
        origin: 'sw'
        bbox_srs: 'EPSG:32643'

globals:

district.xml

<?xml version="1.0"?> 
<Map background-color="blue" srs="+proj=utm +zone=43 +datum=WGS84 +units=m +no_defs" buffer-size="128" minimum-version="0.7.2">

<Style name="District_style_line">
<Rule>
     <MaxScaleDenominator>6600000000</MaxScaleDenominator> 
     <PolygonSymbolizer fill="#ebb1af"/>
     <LineSymbolizer stroke="rgb(0,0,0)" stroke-width="0.98" stroke-linejoin="round"/>
</Rule>
</Style>
<Style name="District_style_text">
    <Rule>
    <MaxScaleDenominator>6600000</MaxScaleDenominator>
    <TextSymbolizer face-name="DejaVu Sans Bold" size="8" fill="black" wrap-width="10" avoid-edges="false" placement="interior">[name]</TextSymbolizer>
    <MinScaleDenominator>2000000</MinScaleDenominator>
    </Rule>
</Style>
<Layer name="District_Boundary" srs="+proj=utm +zone=43 +datum=WGS84 +units=m +no_defs">
    <StyleName>District_style_line</StyleName>
    <StyleName>District_style_text</StyleName>
     <Datasource>
        <Parameter name="dbname">dummydb</Parameter>
        <Parameter name="extent">291627,904686,958569,1426831</Parameter>
        <Parameter name="geometry_field">the_geom</Parameter>
        <Parameter name="host">localhost</Parameter>
        <Parameter name="password">password</Parameter>
        <Parameter name="port">5432</Parameter>
        <Parameter name="srid">32643</Parameter>
        <Parameter name="table">select name,the_geom from districts</Parameter>
        <Parameter name="type">postgis</Parameter>
        <Parameter name="user">testuser</Parameter>
    </Datasource>
</Layer> 

map.js (openlayer2)

var layer = new OpenLayers.Layer.TMS('TMS district', 'http://localhost:8080/tms/', {layername: 'district/distgrid', type: 'png', isBaseLayer:true,transitionEffect:"resize" });
map.addLayer(layer);

Tiles generated like